How to Size a Grain Dryer for Your Farm: Capacity & BPH Guide

Choosing a grain dryer by acreage alone is one of the easiest ways to end up with the wrong machine.

A 2,000-acre farm harvesting mostly dry wheat may need relatively little drying capacity.

Another 2,000-acre farm harvesting damp canola, wet corn or tough cereals during a short weather window may need several times more dryer capacity.

The combine matters.

Yield matters.

Incoming moisture matters.

The number of moisture points you need to remove matters.

Your wet holding capacity matters.

And perhaps most importantly, the dryer has to fit the speed of the entire harvest system around it.

The right question is not:

How many acres do I farm?

It is:

How many wet bushels must I dry per hour during the most demanding realistic part of harvest?

That is what this guide will help you calculate.

If you want a quick estimate before working through the full process, use the free Aglist Grain Dryer Sizing Calculator. It lets you enter your crop, daily grain volume, incoming moisture and target moisture to estimate the dryer capacity your operation needs.

You can also browse the full Grain Dryers category to compare dryer types and individual models.

The Short Answer

A useful starting formula is:

Required dryer throughput = wet bushels that need drying per day ÷ realistic drying hours per day

Then adjust that number for:

• incoming moisture
• target moisture
• crop type
• dryer operating mode
• expected downtime
• wet holding capacity
• future farm growth

For example:

A farm expects to send 10,000 wet bushels per day through the dryer.

If the dryer realistically operates for 20 hours:

10,000 ÷ 20 = 500 BPH

But a 500 BPH brochure rating does not automatically mean a 500 BPH dryer is large enough.

If that 500 BPH rating is based on removing five moisture points and your normal harvest requires eight points of removal, actual throughput can be considerably lower.

The correct machine may therefore need a published capacity well above 500 BPH.

That is why grain dryer sizing should always be done around a specific crop and moisture scenario.

What Does BPH Mean on a Grain Dryer?

BPH means bushels per hour.

It describes how much grain a dryer can process in one hour under a defined set of conditions.

That last part is extremely important.

A grain dryer does not have one universal BPH number.

The same dryer may process:

• 1,000 BPH under one moisture condition
• 700 BPH under another
• 400 BPH under a much wetter condition

without anything being wrong with the machine.

The difference is simply how much water has to be removed from every bushel.

Manufacturers normally publish capacity tables showing throughput at specific incoming and outgoing moisture levels.

For example, an official Sukup centrifugal-dryer specification shows one TC16 configuration rated at up to 740 BPH when drying corn from 20% to 15%, but only 450 BPH when drying from 25% to 15%. It is the same dryer. The additional moisture removal reduces throughput dramatically.

That example explains one of the most important rules in dryer sizing:

Never compare dryer BPH without also comparing moisture removal.

Moisture Points Explained

A moisture point is simply one percentage point of grain moisture.

If grain enters at 18% and leaves at 14%:

18 – 14 = 4 moisture points removed

If corn enters at 25% and leaves at 15%:

25 – 15 = 10 moisture points removed

If canola enters at 12% and your target is 8%:

12 – 8 = 4 moisture points removed

The number of points matters because every additional point means more water has to leave the grain.

More water removal requires:

• more heat
• more airflow
• more residence time
• more fuel
• more dryer capacity

This is why a dryer that looks extremely large on a five-point rating can suddenly look much smaller when asked to remove ten points.

Do Not Assume Moisture Removal Scales Perfectly

It is tempting to use simple math such as:

“If this dryer handles 1,000 BPH at five points, it should handle 500 BPH at ten points.”

That can sometimes provide a rough planning estimate, but real dryer performance is not perfectly linear.

Drying rate changes with:

• grain temperature
• ambient air temperature
• relative humidity
• crop type
• grain cleanliness
• kernel size
• maturity
• airflow
• operating temperature
• dryer design

Manufacturers themselves warn that published capacities are estimates rather than guaranteed farm performance.

Sukup, for example, notes that variety, maturity, cleanliness, weather and management can all affect actual capacity.

Use simple formulas to narrow the range.

Use the manufacturer’s exact capacity chart to choose the final dryer.

Step 1: Determine Your Peak Wet Grain Volume

Start with the busiest realistic harvest day.

Not the average day.

Not your total annual production divided by the number of harvest days.

The dryer needs to survive the days when the combine is working hard and the grain is wet.

Ask:

How many bushels can realistically arrive at the yard in one good harvest day?

This depends on:

• number of combines
• combine capacity
• yield
• crop
• field efficiency
• trucking
• distance between fields and bins
• length of the harvest day

Suppose one combine averages 600 bushels per hour delivered to the yard and harvests effectively for 12 hours.

That is:

600 × 12 = 7,200 bushels/day

If two combines each average 600 BPH:

1,200 × 12 = 14,400 bushels/day

That is the type of number you need.

Use Delivered Bushels, Not Theoretical Combine Capacity

A combine brochure may suggest enormous harvesting capacity.

That does not mean the farm delivers that much grain continuously.

Real output includes:

• headland turns
• unloading delays
• field moves
• breakdowns
• fuel
• transport
• crop changes
• weather
• operator breaks

Use actual historical harvest records whenever possible.

If your best wheat day last year was 11,500 bushels delivered to the yard, that is much more useful than estimating from combine horsepower.

Step 2: Determine How Much of That Grain Actually Needs Drying

Not every bushel harvested during the season necessarily needs the dryer.

A farm may harvest:

• dry wheat
• tough wheat
• dry peas
• damp canola
• wet corn

all during the same season.

If only 40% of your annual production normally requires artificial drying, sizing the dryer against 100% of annual production may result in unnecessary capacity.

But do not use the annual percentage alone.

The real risk is several consecutive days of wet grain.

A better question is:

What is the maximum wet volume I may need to process during a difficult harvest period?

That is your sizing scenario.

Step 3: Know Your Incoming Moisture

Incoming moisture determines how hard the dryer has to work.

For Canadian grain, it is useful to understand the Canadian Grain Commission’s moisture classifications.

For example, CGC currently classifies:

• wheat as tough from 14.6% to 17.0%
• wheat as damp above 17.0%
• canola as tough from 10.1% to 12.5%
• canola as damp above 12.5%
• yellow and green peas as tough from 16.1% to 18.0%
• corn as progressively damp, moist or wet as moisture rises above 17.5%

These are grading classifications, not universal storage targets, but they are useful for understanding how quickly drying requirements can change when harvest conditions deteriorate.

Size Against a Difficult Year, Not a Perfect Year

Imagine your wheat normally enters the dryer at 16%.

Sizing only around that condition may work during an easy fall.

Then a difficult harvest arrives and wheat is coming in at 19%.

Your dryer now has to remove significantly more water from every bushel.

Throughput drops.

The combine keeps harvesting.

The wet bin fills.

Eventually the entire system backs up.

A slightly larger dryer can function like harvest insurance.

That does not mean buying the largest possible machine.

It means designing for a realistic difficult condition rather than the easiest condition you have ever experienced.

Step 4: Define Your Target Moisture

Next determine where the grain needs to end up.

Target moisture depends on:

• crop
• storage length
• grain temperature
• end use
• marketing requirements
• storage system

Do not treat “dry” as one universal number.

For example, long-term canola storage requires particularly careful moisture and temperature management.

The Canola Council of Canada says 8% moisture and grain temperature below 15°C provide a safer target for long-term storage, while higher temperature can increase risk even when moisture appears acceptable.

That is another reason dryer sizing cannot be based on incoming moisture alone.

You need both ends of the equation.

Step 5: Calculate Moisture Points Removed

The basic equation is:

Incoming moisture – target moisture = moisture points removed

Example 1: Wheat

Incoming:

18%

Target:

14.5%

Removal:

3.5 points

Example 2: Canola

Incoming:

12%

Target:

8%

Removal:

4 points

Example 3: Corn

Incoming:

25%

Target:

15%

Removal:

10 points

The corn scenario is dramatically harder even if daily bushel volume is identical.

That is why dryer capacity numbers from corn operations should not automatically be applied to a Prairie wheat operation, or vice versa.

Step 6: Decide How Many Hours Per Day the Dryer Can Actually Run

A dryer can theoretically run 24 hours per day.

Real farms rarely achieve perfect 24-hour utilization indefinitely.

There may be time required for:

• cleaning
• maintenance
• loading interruptions
• emptying
• moisture checks
• crop changes
• burner issues
• power interruptions
• wet-bin problems
• takeaway problems

A farm with a well-designed continuous-flow system may operate close to continuously.

A batch dryer will naturally have more cycling.

For planning purposes, use a realistic operating window rather than assuming 24 perfect hours.

Common planning scenarios might be:

• 12 hours/day
• 16 hours/day
• 20 hours/day
• near-continuous 24-hour operation

The right number depends on your system.

Required BPH Example

Suppose:

Daily wet grain = 12,000 bu

Realistic dryer operation = 20 hr/day

Required average throughput:

12,000 ÷ 20 = 600 BPH

That means the dryer must average at least 600 wet bushels per hour under the actual moisture condition you expect.

Not 600 BPH at some unrelated brochure condition.

Add a Capacity Margin

Sizing a dryer to operate at exactly 100% of required capacity every hour leaves very little room for problems.

Consider some additional margin for:

• unexpectedly wetter grain
• cooler weather
• dirty grain
• minor downtime
• future yield increases
• a larger combine later
• field expansion

A planning margin of roughly 15% to 25% can be reasonable in many situations, but it should not be treated as a universal engineering standard.

For example:

Required average = 600 BPH

Add 20% planning margin:

600 × 1.20 = 720 BPH

Now you are looking for a dryer capable of roughly 720 BPH under your real crop and moisture scenario.

Why a Capacity Buffer Matters

A dryer operating at 70% to 85% of its practical limit has room to react.

A dryer operating continuously at 100% has no room.

If grain gets slightly wetter, the wet holding bin begins gaining inventory.

If the combines harvest faster, inventory grows again.

If the dryer stops for an hour, there may be no way to catch back up.

The extra capacity is not necessarily wasted.

It creates recovery capability.

But Oversizing Has a Cost Too

Bigger is not always better.

A much larger dryer can mean:

• higher capital cost
• larger electrical service
• bigger burners
• more expensive installation
• greater wet holding requirements
• larger takeaway equipment
• more complicated infrastructure

If a 700 BPH dryer comfortably handles your worst realistic workload, installing a 2,500 BPH system may provide little value.

The ideal dryer is not the largest machine you can afford.

It is the smallest machine that comfortably handles your realistic peak requirement with appropriate reserve.

Quick Capacity Planning Table

Here is a simple example based only on daily volume and operating time.

This table does not adjust for crop or moisture removal.

Wet grain per day	16 hr/day	20 hr/day	24 hr/day
3,000 bu	188 BPH	150 BPH	125 BPH
5,000 bu	313 BPH	250 BPH	208 BPH
7,500 bu	469 BPH	375 BPH	313 BPH
10,000 bu	625 BPH	500 BPH	417 BPH
15,000 bu	938 BPH	750 BPH	625 BPH
20,000 bu	1,250 BPH	1,000 BPH	833 BPH
25,000 bu	1,563 BPH	1,250 BPH	1,042 BPH
30,000 bu	1,875 BPH	1,500 BPH	1,250 BPH
40,000 bu	2,500 BPH	2,000 BPH	1,667 BPH
50,000 bu	3,125 BPH	2,500 BPH	2,083 BPH

Again, these are only starting numbers.

A farm needing 1,000 BPH while removing three moisture points and a farm needing 1,000 BPH while removing ten points do not need the same dryer.

Use the Aglist Grain Dryer Sizing Calculator

Instead of doing all of the first-stage math manually, use the Aglist Grain Dryer Sizing Calculator.

Enter:

• crop
• daily bushels
• incoming moisture
• target moisture
• available drying time

The calculator estimates the capacity class required for the job.

Use that number to narrow your options.

Then verify the exact crop and moisture capacity against the manufacturer’s performance table for the specific model.

That final verification is important.

A calculator is a planning tool.

The manufacturer’s capacity chart describes the actual machine.

Step 7: Compare Dryers at the Same Moisture Removal

This is one of the most important steps.

Suppose you are comparing Dryer A and Dryer B.

Dryer A:

1,300 BPH at 20% to 15%

Dryer B:

900 BPH at 25% to 15%

You cannot conclude Dryer A is larger.

The moisture conditions are different.

Find the same reference condition for both dryers.

Ideally compare:

• same crop
• same incoming moisture
• same outgoing moisture
• same drying mode

Then the numbers become meaningful.

Example: Why Moisture Conditions Change Everything

Sukup publishes examples where the same dryer drops from 740 BPH at 20% to 15% corn to 450 BPH when drying from 25% to 15%.

That is roughly a 39% reduction in throughput simply because more moisture must be removed.

This is why a dryer advertised as “700 BPH” is incomplete information.

The next question should always be:

700 BPH at what moisture removal?

Full Heat vs Dry and Cool

Dryer operating mode can also dramatically change capacity.

Full Heat

In full-heat operation, grain leaves the dryer hot.

Cooling happens later in the storage bin.

Because the dryer is not spending as much of its internal capacity cooling grain, throughput can be significantly higher.

Dry and Cool

The dryer uses part of the machine for cooling.

Grain exits closer to storage temperature.

Throughput is usually lower because part of the dryer is no longer being used only for moisture removal.

Neither method is automatically better.

Full heat can maximize dryer throughput, but it requires properly designed cooling bins.

Sukup says hot grain from its full-heat cross-flow dryers generally leaves around 120°F to 150°F and must then be cooled with adequate bin airflow. The company recommends approximately 1/3 CFM per bushel in a full bin, or about 12 CFM for each BPH of dryer output.

The dryer and bin therefore have to be sized as one system.

Cooling Capacity Can Limit Dryer Capacity

Imagine a dryer capable of 1,500 BPH full heat.

If the cooling bin cannot handle that stream of hot grain safely, you do not really have a 1,500 BPH drying system.

You have a 1,500 BPH dryer connected to an undersized cooling system.

This is a recurring theme in grain handling.

The slowest component determines total system capacity.

Step 8: Size the Wet Holding Bin

A good wet holding system separates combine timing from dryer timing.

Without wet holding, the dryer effectively has to follow the combine minute by minute.

With wet holding, the combine can harvest faster than the dryer temporarily.

The dryer then continues processing after the combines stop.

That is extremely valuable.

Iowa State guidance recommends planning wet holding capacity around the difference between harvest inflow and what the dryer can process during harvest hours. It notes that roughly four to eight hours of harvest capacity is a common minimum planning range, while some operations plan for a full day.

Wet Holding Example

Suppose combines deliver:

1,200 BPH

Dryer processes:

800 BPH

Harvest continues for:

12 hours

During harvest, wet inventory grows at:

1,200 – 800 = 400 BPH

After 12 hours:

400 × 12 = 4,800 bushels

You therefore need more than 4,800 bushels of usable wet holding just to prevent the system from filling during that harvest period.

And that assumes:

• dryer never stops
• grain inflow never exceeds 1,200 BPH
• bin capacity is completely usable
• no previous wet grain remains

Real planning should include additional reserve.

Why a Larger Wet Bin Can Make a Smaller Dryer Work

This is an important system-design concept.

You may not need the dryer to match the combine instantaneously.

If you harvest for 12 hours but dry for 20 or 24 hours, the wet bin acts as a buffer.

Example:

Harvest:

15,000 bu over 12 hours.

Dryer:

750 BPH for 20 hours.

Drying capacity:

750 × 20 = 15,000 bu/day

The dryer can process the entire daily harvest even though the combine delivers grain much faster during field hours.

The wet bin makes the mismatch possible.

Without wet holding, 750 BPH would appear far too small.

Step 9: Check Load and Unload Equipment

A perfectly sized dryer can still become a bottleneck if grain cannot get into or out of it fast enough.

Check the rated capacity of:

• wet grain auger
• bucket elevator
• drag conveyor
• dryer loading auger
• dryer unloading system
• dry grain conveyor
• cooling-bin fill system

If the dryer processes 1,200 BPH but the takeaway conveyor moves only 900 BPH, total capacity is 900 BPH.

The same rule applies upstream.

A dryer starved for wet grain cannot operate at rated capacity.

Design Handling Capacity Above Dryer Capacity

Ideally, grain handling equipment should have some reserve above normal dryer output.

A dryer operating at 1,000 BPH should not be connected to a conveyor that barely handles exactly 1,000 BPH under perfect conditions.

Why?

Capacity can fall when:

• grain is dirty
• augers wear
• crop changes
• conveyor angle changes
• grain moisture rises
• equipment is partially restricted

Additional handling reserve helps keep the dryer continuously fed.

Step 10: Check Electrical Requirements

A larger dryer may require electrical infrastructure the farm does not currently have.

Before settling on dryer size, check:

• service voltage
• single-phase vs three-phase
• available amperage
• fan horsepower
• burner controls
• conveyors
• auxiliary motors

Electrical upgrades can become a significant part of the installation.

This is particularly important when moving from a small batch dryer to a large continuous-flow system.

The dryer itself may be only one part of the investment.

Single-Phase vs Three-Phase

Smaller dryers may be available with single-phase power.

As capacity increases, three-phase becomes increasingly common because large fans and conveying systems require substantial electrical power.

If three-phase service is not readily available, that can affect which models are practical.

This is one reason smaller PTO-driven batch dryers remain attractive on some farms.

For example, Aglist currently lists the GT 245XL at 140 BPH for a five-point reference condition and the GT 300 at 235 BPH, both representing a much simpler class of drying system than a large commercial tower.

Step 11: Natural Gas or Propane

Fuel availability can influence dryer size and operating strategy.

Large dryers consume substantial energy.

The basic options commonly include:

• propane
• natural gas

Propane gives farms flexibility where natural gas infrastructure is unavailable.

Natural gas can be attractive for high-volume permanent installations where service is available.

But fuel choice should be considered before finalizing dryer capacity because the required:

• burner supply
• regulators
• piping
• storage
• delivery system

must support the dryer’s maximum demand.

A dryer designed for high BPH is useless if the fuel infrastructure cannot feed it properly.

Step 12: Consider Your Crop Mix

Do not size a mixed-farm dryer around only one crop unless that crop clearly creates the worst case.

A Saskatchewan operation might grow:

• wheat
• canola
• barley
• peas
• oats
• flax

Each behaves differently in a dryer.

The farm’s hardest drying scenario could be:

• damp canola that needs careful heat management
• wet late wheat
• high-volume barley
• unusually wet corn

Find the scenario that creates the most pressure on your harvest system.

Size around that scenario.

Sizing a Dryer for Wheat

Wheat can look relatively easy until harvest conditions become wet.

The Canadian Grain Commission classifies wheat at 14.6% to 17.0% as tough and above 17.0% as damp.

A farm normally bringing in 15.5% wheat may need relatively modest moisture removal.

Another farm forced to harvest at 19% has a completely different drying job.

Wheat sizing example

Peak daily wheat:

12,000 bu

Incoming moisture:

18%

Target:

14.5%

Moisture removal:

3.5 points

Dryer operating window:

20 hours

Base throughput:

12,000 ÷ 20 = 600 BPH

Now apply reasonable operating reserve and verify that the dryer can actually maintain the required capacity at approximately 3.5 points of wheat moisture removal.

Do not simply select a machine because the brochure says 600 BPH at a completely different corn condition.

Sizing a Dryer for Canola

Canola requires more caution because excessive heat can damage seed and storage risk depends strongly on both moisture and temperature.

The Canadian Grain Commission classifies canola as:

• straight below 10.1%
• tough from 10.1% to 12.5%
• damp above 12.5%

For long-term storage, the Canola Council recommends paying close attention to both moisture and temperature and describes 8% moisture with seed below 15°C as a safer target.

The Canola Council also recommends continuous-flow or recirculating batch systems for tough and damp canola because they can reduce the risk of seed damage compared with some more aggressive drying approaches.

Canola sizing example

Peak daily canola:

8,000 bu

Incoming:

12%

Target:

8%

Removal:

4 points

Available dryer time:

20 hr

Base requirement:

8,000 ÷ 20 = 400 BPH

Add a planning buffer and you might begin comparing machines capable of roughly 480 to 500 BPH under the actual canola temperature and moisture conditions.

But this is exactly where brochure corn capacity becomes particularly unreliable.

Canola temperature limits may force slower operation.

Always confirm crop-specific settings and capacity.

Sizing a Dryer for Corn

Corn can create some of the highest drying loads on a farm because moisture removal may be substantial.

A continuous-flow dryer rated very strongly at 20% to 15% may lose a large amount of throughput when asked to dry 25% corn to the same target.

Official dryer tables demonstrate this clearly.

For example, Sukup lists certain centrifugal machines at approximately 740 BPH for 20% to 15% but 450 BPH for 25% to 15%.

Corn sizing example

Daily wet corn:

20,000 bu

Incoming:

25%

Target:

15%

Drying hours:

22

Base requirement:

20,000 ÷ 22 = 909 BPH

But this means you need roughly 909 BPH while removing 10 moisture points.

A dryer rated 1,000 BPH at five points may be nowhere near large enough.

You need to look specifically at its 25% to 15% rating.

Sizing for Barley

Barley often fits into the same general farm drying system as wheat, but grain quality and end use can affect how aggressively it should be handled.

CGC classifies many barley classes as tough beginning around 13.6% moisture and damp above 17%.

For a mixed wheat and barley operation, compare the worst normal moisture removal for both crops.

The crop producing the lower real dryer throughput should drive the capacity decision.

Sizing for Peas and Other Pulses

Pulses can require gentler handling than commodity corn.

Cracking and seed damage can matter.

The Canadian Grain Commission classifies green and yellow peas as tough between 16.1% and 18% and damp above 18%.

When drying pulses, do not assume the highest possible burner temperature is the best strategy.

If grain quality forces lower temperatures, real BPH can fall.

Again, the correct dryer is the one that meets your required throughput under the settings you actually intend to use.

How Farm Size Relates to Dryer Size

Acreage can still be useful as a secondary check.

It just should not be the primary calculation.

Two 5,000-acre farms can need completely different systems.

Farm A

5,000 acres

One combine

Mostly wheat and pulses

Large amount normally harvested dry

Moderate daily wet volume

A mid-size dryer may be enough.

Farm B

5,000 acres

Two combines

Large canola acreage

Short harvest window

Frequent tough grain

Much higher peak wet volume

Farm B may need dramatically more drying capacity even though acreage is identical.

Example Dryer Capacity Classes

These are useful planning categories, not rigid rules.

Under 400 BPH

Common applications:

• smaller mixed farms
• occasional tough grain
• batch drying
• farms with long available drying windows

Examples on Aglist include:

GT 245XL

GT 300

GT RB500

Batch dryers can make sense where simple operation is more important than continuous high-volume flow.

Roughly 400 to 1,300 BPH

This is a major farm-scale continuous-flow range.

It can fit:

• larger single-combine operations
• some two-combine farms
• farms with good wet holding
• farms drying substantial cereal or oilseed volumes

Examples include several portable GSI and Super-B configurations.

The GSI 1226 is one example of a portable continuous-flow dryer in this general capacity class.

The Super-B SQ12 represents the smaller end of Super-B’s modern continuous-flow range.

The Super-B SQ24 moves considerably farther into high-volume farm drying.

Roughly 1,300 to 4,000 BPH

At this level, infrastructure becomes increasingly important.

Typical systems may include:

• larger continuous-flow dryers
• mixed-flow dryers
• tower dryers
• large wet holding bins
• dedicated elevators or drag conveyors
• three-phase electrical service
• high-capacity gas infrastructure

Sukup currently lists mixed-flow systems from roughly 700 to 4,000 BPH under its specified 20% to 15% reference condition.

This capacity class can serve large farms, multi-combine operations and some commercial applications.

4,000 BPH and Above

Once dryer requirements reach several thousand bushels per hour, the project becomes less about choosing one piece of machinery and more about designing a grain handling facility.

Large tower dryers can reach well beyond normal farm portable-dryer capacity.

Sukup, for example, currently lists its tower dryers from approximately 1,800 to 12,000 BPH depending on size and configuration.

At that scale you need to design:

• wet storage
• receiving
• conveying
• cooling
• dry storage
• electrical service
• fuel supply
• automation

around the dryer.

Putting a 5,000 BPH dryer into a 1,500 BPH grain-handling system accomplishes nothing.

Batch vs Continuous Flow for Sizing

Dryer type matters because BPH is not experienced the same way.

Batch dryer

A batch dryer:

1. fills
2. dries
3. possibly cools
4. unloads
5. reloads

There are natural interruptions between cycles.

This makes batch size and cycle time extremely important.

If a dryer holds 500 bushels and completes a full cycle in two hours:

500 ÷ 2 = 250 BPH average

The 500-bushel holding capacity does not mean it dries 500 BPH.

Continuous-flow dryer

Wet grain enters continuously while dry grain leaves continuously.

Once stabilized, the system can operate near a relatively consistent throughput.

For farms receiving a steady stream of grain from multiple combines, continuous flow can make the overall system easier to balance.

Mixed-Flow Dryers

Mixed-flow dryers use alternating air ducts to move heated air through the grain.

They are often considered where:

• high throughput
• grain quality
• reduced screen maintenance
• fuel efficiency

are priorities.

Their BPH should still be evaluated using the same process:

crop + incoming moisture + target moisture + operating mode

Dryer architecture does not eliminate the need for sizing.

Portable vs Tower Dryer

Portable dryers cover a huge part of the farm market because they can provide serious throughput without the scale of a permanent commercial tower.

Tower dryers become attractive as daily volumes rise and the dryer becomes the centre of a large permanent grain system.

The transition point is not simply acreage.

It happens when required BPH, fuel use, labour and infrastructure begin making a larger permanent system more practical.

For a broader look at available systems, see Best Grain Dryers in Canada.

Example 1: Smaller Prairie Mixed Farm

Assume:

4,000 wet bu/day

One combine

Wheat and canola

20 dryer hours/day

Base requirement:

4,000 ÷ 20 = 200 BPH

Add approximately 20% planning reserve:

240 BPH

A smaller batch or portable system may be enough.

The operation may not gain anything from a 1,000 BPH continuous dryer.

Models in the GT family are worth investigating for this type of capacity requirement.

Example 2: Larger Single-Combine Operation

Assume:

10,000 wet bu/day

20 dryer hours

Base:

500 BPH

20% reserve:

600 BPH

Now continuous-flow equipment becomes much more attractive.

Possible machines to investigate might include:

• GSI portable dryers
• Super-B SQ models
• Vertec continuous-flow dryers

You can compare GSI grain dryers, the Super-B Grain Dryers guide and Vertec grain dryers on Aglist.

Example 3: Two-Combine Prairie Farm

Assume:

20,000 wet bu/day

20 dryer hours

Base:

1,000 BPH

20% reserve:

1,200 BPH

This is already a serious continuous-flow operation.

Wet holding becomes extremely important.

If the combines deliver 2,000 BPH during field hours while the dryer processes 1,200 BPH, wet storage absorbs the difference.

Supporting conveyors, electrical infrastructure and fuel supply must all be sized accordingly.

A model such as the Super-B SQ24 or comparable GSI equipment may enter the discussion depending on crop and moisture requirements.

Example 4: Large High-Volume Operation

Assume:

40,000 wet bu/day

22 drying hours

Base:

1,818 BPH

20% reserve:

approximately 2,180 BPH

Now the project is moving into high-capacity mixed-flow or tower territory.

At this level, the dryer should not be selected before answering:

• What is wet holding capacity?
• How fast can grain be received?
• How fast can dry grain leave?
• Is three-phase power available?
• Can natural gas supply meet burner demand?
• Where will hot grain be cooled?
• How much future expansion is expected?

Dryer sizing has become grain-system design.

Should the Dryer Match Combine BPH?

Not necessarily.

This is a common misunderstanding.

Suppose the combine system delivers 1,500 BPH for 10 hours.

Daily production:

15,000 bu

If your dryer can run 20 hours, it only needs to average:

750 BPH

provided you have enough wet holding.

So the dryer does not necessarily need to match 1,500 BPH instantaneous combine output.

It must match daily wet production over the available drying window.

That distinction can save a farm from installing significantly more dryer than necessary.

When the Dryer Should Match Combine Output More Closely

There are situations where closer matching makes sense.

For example:

• little wet holding is available
• harvest must continue around the clock
• grain cannot safely remain wet for long
• multiple combines create extreme inflow
• custom drying customers require rapid turnaround

In those cases, instantaneous throughput becomes more important.

How Much Wet Holding Do You Need?

There is no single universal number.

But think in terms of hours of harvest rather than only total bushels.

Suppose your combines deliver:

1,500 BPH

Four hours of wet holding:

6,000 bu

Eight hours:

12,000 bu

Twelve hours:

18,000 bu

A larger wet bin gives the drying system more flexibility.

But very wet grain also cannot simply sit indefinitely.

Aeration and grain condition must be managed carefully.

Iowa State’s grain handling guidance emphasizes that wet holding capacity allows drying to continue through harvest interruptions and that storage design needs to be integrated with dryer performance.

Do Not Forget Wet Bin Aeration

The wet bin is not just a waiting room.

Wet grain is biologically active and at higher spoilage risk.

Aeration can help control grain temperature while it waits.

The required airflow depends on:

• crop
• moisture
• bin depth
• holding time
• grain temperature

The wetter the grain, the less forgiving the system becomes.

This is especially important with damp canola.

The Canola Council recommends conditioning damp canola quickly and warns that high-moisture canola has a high spoilage risk if it cannot be dried promptly.

Future-Proofing Your Dryer Size

A grain dryer can remain on a farm for many years.

Ask what the operation might look like later.

Will you:

• add acreage?
• increase yields?
• move to a larger combine?
• add a second combine?
• grow more corn?
• expand grain storage?
• do custom drying?

If a farm expects to move from 8,000 wet bushels/day to 12,000 within several years, installing a dryer sized exactly for 8,000 may create an expensive upgrade later.

Some dryer systems are expandable.

Others are not.

Expansion capability can therefore matter almost as much as current BPH.

But Do Not Size for an Imaginary Farm

Future-proofing should be realistic.

If there is no practical chance the operation will double in size, paying for twice the needed drying capacity today may not make sense.

Plan around:

realistic growth + realistic difficult harvest conditions

not every possible future scenario.

Common Grain Dryer Sizing Mistakes

Mistake 1: Choosing by acreage

Acreage tells you very little about peak wet grain flow.

Use bushels per day.

Mistake 2: Looking at BPH without moisture removal

A 1,000 BPH five-point rating is not a 1,000 BPH ten-point rating.

Mistake 3: Assuming the dryer can run perfectly 24/7

Maintenance and interruptions happen.

Include realistic operating time.

Mistake 4: Ignoring wet holding

The wet bin is what allows the combine and dryer to operate at different speeds.

Mistake 5: Undersizing takeaway equipment

A fast dryer with a slow conveyor becomes a slow system.

Mistake 6: Ignoring cooling

Full-heat capacity depends on what happens after grain leaves the dryer.

Mistake 7: Using corn specifications for every crop

Crop behaviour and safe drying temperature vary.

Mistake 8: Buying around an average year

Dryer problems happen during difficult harvests, not ideal ones.

Mistake 9: Oversizing dramatically

Unused dryer capacity still costs money.

Mistake 10: Ignoring electrical service

A larger dryer can trigger major infrastructure upgrades.

Mistake 11: Ignoring fuel supply

The burner has to receive enough fuel at full load.

Mistake 12: Ignoring future harvest capacity

A larger combine can turn today’s perfectly sized dryer into tomorrow’s bottleneck.

How to Read a Grain Dryer Spec Sheet

When comparing individual dryers, find these numbers:

Capacity

Look for BPH at several moisture conditions.

Crop used for rating

Most North American ratings are based on specific corn conditions.

Wet or dry bushels

Confirm what the manufacturer means.

Drying mode

Check whether the number represents:

• full heat
• dry and cool
• continuous flow
• staged batch

Holding capacity

This tells you how much grain is physically inside the dryer.

It is not the same as hourly capacity.

Fan horsepower

Larger systems require more airflow and electrical capacity.

Burner output

Usually given in BTU/h.

Electrical requirement

Check phase, voltage and amperage.

Fuel

Confirm LP, natural gas or available conversion.

Load and unload capacity

These must support the dryer.

A Real Model Example: GSI 1226

Aglist’s GSI 1226 grain dryer page provides a useful example of why mode matters.

The dryer has different published throughput depending on whether it operates in Full Heat or Dry & Cool.

A farm comparing that model should therefore decide how grain will be cooled before using one of its BPH ratings for sizing.

That same principle applies across brands.

A Real Batch Example: GT RB500

The GT RB500 is a 500-bushel recirculating batch dryer.

Its physical holding capacity is much greater than its hourly drying rate.

That illustrates another important sizing principle:

bushels inside the dryer are not the same thing as bushels dried per hour.

For batch dryers, cycle time determines throughput.

A Real Continuous-Flow Example: Super-B SQ24

The Super-B SQ24 is a much larger continuous-flow system.

Aglist lists different published corn capacities depending on moisture removal and operating configuration.

Again, there is no single universal SQ24 BPH.

The correct number depends on how the dryer is being used.

For more on the lineup, read the Super-B Grain Dryers Complete Canadian Guide.

What Size Grain Dryer for One Combine?

There is no reliable answer without more information.

A single combine may deliver:

• 300 BPH
• 600 BPH
• 1,000+ BPH

depending on crop and yield.

A better process is:

1. Find peak wet bushels/day.
2. Decide how many drying hours are available.
3. Calculate base BPH.
4. Determine worst realistic moisture removal.
5. Add capacity margin.
6. Compare actual dryer performance.

One combine does not automatically mean a small dryer.

What Size Grain Dryer for Two Combines?

The same rule applies.

Two combines dramatically increase potential grain inflow, but wet holding can allow the dryer to run at a lower rate than instantaneous harvest output.

If two combines deliver 20,000 wet bushels/day and the dryer operates 20 hours:

20,000 ÷ 20 = 1,000 BPH base requirement

Then adjust for moisture and reserve.

That is a far better sizing method than simply selecting a dryer labelled “for two combines.”

Is 500 BPH Enough?

500 BPH can process:

• 8,000 bu in 16 hours
• 10,000 bu in 20 hours
• 12,000 bu in 24 hours

under the condition where it genuinely achieves 500 BPH.

Whether that is enough depends on your farm.

If the dryer falls to 300 BPH during wetter conditions, daily capacity changes completely.

Always use the worst realistic operating rate.

Is 1,000 BPH Enough?

At a true 1,000 BPH:

• 16 hr = 16,000 bu/day
• 20 hr = 20,000 bu/day
• 24 hr = 24,000 bu/day

That is substantial capacity for many farm operations.

But again, if the manufacturer’s 1,000 BPH rating is based on five moisture points and your normal requirement is ten points, your actual output may be much lower.

Is 2,000 BPH Enough?

At a genuine 2,000 BPH:

• 16 hr = 32,000 bu/day
• 20 hr = 40,000 bu/day
• 24 hr = 48,000 bu/day

At this point, grain handling infrastructure becomes increasingly important.

A 2,000 BPH dryer needs a system around it capable of receiving, cooling and moving that volume.

What If the Dryer Is Too Small?

An undersized dryer can create a chain reaction:

1. Wet bin fills.
2. Dryer cannot catch up.
3. Trucks have nowhere to unload.
4. Combines slow down.
5. Combines stop.
6. Good harvest weather is wasted.

The dryer has become the harvest bottleneck.

In a short Prairie weather window, that can be much more expensive than the dryer capacity saved during installation.

What If the Dryer Is Too Large?

An oversized dryer creates a different problem.

You may pay for:

• unused capacity
• larger electrical infrastructure
• larger gas service
• bigger wet storage
• more expensive conveyors

without actually shortening harvest.

A dryer cannot fix bottlenecks elsewhere in the system.

If trucks are the problem, a bigger dryer does not help.

If combines are the problem, a bigger dryer waits.

If storage is full, a bigger dryer waits.

Find the Real Bottleneck

Before increasing dryer size, ask what actually stops harvest first.

Is it:

• combine capacity?
• trucking?
• wet holding?
• dryer capacity?
• cooling?
• dry grain handling?
• storage?
• labour?

The best grain system increases capacity at the actual bottleneck.

Not necessarily at the most visible machine.

Final Grain Dryer Sizing Checklist

Before selecting a dryer, write down:

Harvest

• peak wet bushels/day
• number of combines
• realistic harvesting hours
• expected future harvest capacity

Grain

• primary crops
• normal incoming moisture
• difficult-year moisture
• target moisture
• grain-quality requirements

Dryer

• BPH at the correct moisture removal
• full heat or dry and cool
• batch or continuous flow
• available expansion

Wet side

• wet bin capacity
• aeration
• receiving rate
• dryer loading rate

Dry side

• dryer unload capacity
• conveyor/elevator capacity
• cooling-bin airflow
• storage capacity

Utilities

• propane or natural gas
• available fuel flow
• electrical phase
• voltage
• amperage

Operations

• expected dryer hours/day
• maintenance downtime
• labour
• automation
• remote monitoring

If any of those parts are missing, the dryer sizing calculation is incomplete.

The Best Way to Size a Grain Dryer

Start with the farm, not the dryer brochure.

Calculate how many wet bushels arrive during your hardest realistic harvest days.

Determine how many hours the dryer can operate.

Calculate your base BPH requirement.

Then account for crop and moisture removal.

Add a reasonable capacity margin.

Make sure wet holding, loading, cooling, fuel, electricity and takeaway equipment can support that rate.

Only then should you start comparing individual dryers.

A smaller farm may discover that a 250 BPH batch dryer comfortably handles its entire drying requirement.

Another farm may genuinely need 2,000 BPH or more.

Neither dryer is better.

The correctly sized dryer is the one that keeps harvest moving without forcing the farm to pay for capacity it cannot use.

Use the Aglist Grain Dryer Sizing Calculator to estimate your required capacity, then browse Grain Dryers on Aglist to compare models that fit the result.

For broader equipment selection, see Best Grain Dryers in Canada.

Frequently Asked Questions

How do I calculate what size grain dryer I need?

Start with the number of wet bushels that need drying on a peak day and divide by the number of hours the dryer can realistically operate. Then adjust for crop type, incoming moisture, target moisture, operating mode and expected downtime.

What does BPH mean for a grain dryer?

BPH means bushels per hour. It represents dryer throughput under a specific crop, moisture-removal and operating condition.

How many BPH do I need for 10,000 bushels per day?

If the dryer runs for 20 hours, the base requirement is 500 BPH. If it runs for 16 hours, the base requirement is 625 BPH. You then need to adjust for moisture removal and add appropriate operating reserve.

Should grain dryer capacity match combine capacity?

Not necessarily. A wet holding bin allows the combine to deliver grain faster than the dryer processes it. What matters is whether the dryer can process the total daily wet volume before the next harvest cycle creates a bottleneck.

How much larger should my dryer be than my calculated requirement?

There is no universal margin. A planning allowance around 15% to 25% may be reasonable for some farms to account for wetter grain, downtime and future growth, but the correct reserve depends on the operation.

Why does grain dryer BPH decrease with wetter grain?

Wetter grain contains more water that must be evaporated. More moisture removal requires greater heat input and longer residence time, so fewer bushels can move through the dryer each hour.

Is a 500 BPH grain dryer enough for one combine?

It can be, but the answer depends on daily wet grain volume and moisture removal. A true 500 BPH dryer can theoretically process 10,000 bushels in 20 hours, but actual capacity may be lower in wetter grain.

Is a 1,000 BPH dryer enough for two combines?

Possibly. If two combines produce 20,000 wet bushels per day and the dryer runs 20 hours, 1,000 BPH is the base daily requirement. Moisture removal, downtime and reserve still need to be considered.

How does incoming moisture affect grain dryer capacity?

It can affect capacity dramatically. The more moisture points removed, the slower a given dryer normally processes grain.

Is grain dryer capacity usually rated on wet or dry bushels?

Manufacturer capacity tables commonly describe wet bushels entering the dryer, but always check the specific manufacturer’s definition and test conditions.

Should I size my dryer for an average harvest?

Usually not. Size around a realistic difficult harvest condition so wetter grain does not immediately turn the dryer into a bottleneck.

How large should a wet holding bin be?

It should be large enough to absorb the difference between harvest inflow and dryer throughput during the harvest period. Several hours of combine output can provide useful buffering, while some farms plan for much more.

Does a bigger wet bin reduce the dryer size I need?

It can. Wet holding allows grain harvested during a short field window to be dried over a longer period, reducing the BPH required from the dryer itself.

Is full-heat drying faster than dry and cool?

Usually yes because more of the dryer can be devoted to heating and moisture removal. However, full-heat systems require adequate cooling capacity after grain leaves the dryer.

What is the difference between holding capacity and drying capacity?

Holding capacity is the amount of grain physically inside the dryer. Drying capacity is how many bushels the machine can process per hour. They are not the same.

Should I choose a batch or continuous-flow dryer?

Batch dryers can suit smaller or variable-volume operations and provide simple control over individual loads. Continuous-flow dryers are generally better suited to steady, higher-volume harvest systems.

Can acreage tell me what size grain dryer I need?

Not accurately by itself. Yield, crop type, moisture, combine output and harvest window matter more than acreage.

Should I size a dryer for future expansion?

Consider realistic growth such as additional acres, higher yields or another combine. Avoid paying for extreme capacity that the farm is unlikely to use.

What is the easiest way to estimate grain dryer size?

Use the Aglist Grain Dryer Sizing Calculator, then verify the result against the specific manufacturer’s capacity table at your crop and moisture conditions.

Related Grain Dryer Resources

• Grain Dryer Sizing Calculator – estimate BPH from crop, daily volume and moisture removal.
• Grain Dryers – browse the main Aglist grain dryer category.
• Best Grain Dryers in Canada – compare dryer types and selection factors.
• GSI Grain Dryers – browse GSI portable and high-capacity dryers.
• Super-B Grain Dryers – browse the Super-B lineup.
• Super-B Grain Dryers Canadian Guide – detailed guide to the SQ Series.
• Vertec Grain Dryers – explore Vertec continuous-flow dryers.
• GSI 1226 – portable continuous-flow example.
• GT 245XL – smaller recirculating batch example.
• GT 300 – 350-bushel batch dryer.
• GT RB500 – larger recirculating batch option.
• Super-B SQ12 – smaller continuous-flow Super-B.
• Super-B SQ24 – higher-capacity Super-B comparison point.

Dryer capacities are planning and manufacturer performance figures, not guaranteed field output. Actual throughput can vary with crop, incoming moisture, grain temperature, cleanliness, ambient weather, operating temperature, dryer configuration and management. Confirm critical capacity, fuel, electrical and installation requirements with the current manufacturer documentation and your equipment supplier before final system design.