A standard semi-truck holds roughly 900 to 1,100 bushels of corn, depending on the trailer’s volume and how much the load weighs. The most commonly cited figure is about 910 bushels at the federal weight limit of 80,000 pounds gross vehicle weight, according to the U.S. Army Corps of Engineers. But the actual number you can haul depends on the trailer size, the corn’s moisture content, and your state’s weight rules.
How the 910-Bushel Figure Works
Federal law caps a standard five-axle semi at 80,000 pounds gross vehicle weight, which includes the truck, trailer, and cargo. A typical tractor and hopper-bottom grain trailer together weigh around 30,000 to 34,000 pounds empty, leaving roughly 46,000 to 50,000 pounds for corn. At the standard test weight of 56 pounds per bushel (the baseline for No. 1 yellow corn in the U.S.), that math works out to about 820 to 890 bushels if weight is the limiting factor.
The 910-bushel estimate from the Corps of Engineers assumes a payload of about 26 tons (52,000 pounds), which lines up with a lighter tractor-trailer combination. In practice, most drivers land somewhere between 850 and 1,000 bushels per load, depending on their equipment and how close they run to the weight limit.
Why Test Weight Changes the Count
Not all corn weighs the same per bushel. A bushel is a unit of volume (about 1.24 cubic feet), and the actual weight of corn that fills that space varies with the density of the kernels. The U.S. standard is 56 pounds per bushel for No. 1 yellow corn, while No. 2 yellow corn has a minimum of 54 pounds per bushel.
This matters because grain elevators pay you based on 56-pound “market bushels,” not by volume. If you fill a trailer with 1,000 volumetric bushels of corn that tests at only 52 pounds per bushel, the elevator calculates your payment as 929 market bushels (52,000 pounds divided by 56). You get paid less and may also receive a discounted price per bushel for the low test weight.
The flip side works in your favor. If your corn tests at 60 pounds per bushel, those same 1,000 volumetric bushels count as 1,071 market bushels at the elevator (60,000 pounds divided by 56). The catch is that heavier corn means you hit the truck’s weight limit sooner, so you may need to haul fewer volumetric bushels to stay legal.
How Moisture Affects What You Can Haul
Corn moisture and test weight move in opposite directions. Wetter corn is lighter per bushel because the extra moisture takes up space without adding as much density. As corn dries, either in the field or in a grain dryer, test weight goes up as long as the kernels stay intact.
A simple formula from Purdue University estimates this relationship: multiply the test weight at the higher moisture by (100 minus the dry moisture percentage) divided by (100 minus the wet moisture percentage). For example, corn at 25% moisture with a 52-pound test weight would test around 58.9 pounds per bushel once dried to 15% moisture. That’s a significant jump that changes how many bushels fit within your weight limit.
If you’re hauling freshly harvested corn at higher moisture, you can often fit more volumetric bushels on the truck because each one weighs less. But you’ll receive fewer market bushels at the elevator. Drier corn is denser, so your trailer fills the weight limit faster, but each bushel is worth more at delivery.
Trailer Size and Type
Most grain is hauled in hopper-bottom trailers, which typically hold between 900 and 1,100 cubic feet of cargo space. A trailer on the larger end can physically hold over 1,000 volumetric bushels, but whether you can legally load that much depends on weight.
Lighter aluminum trailers weigh less than steel ones, giving you more payload capacity. Upgrading from a steel to an aluminum hopper can free up 2,000 to 4,000 pounds, which translates to roughly 35 to 70 extra bushels of corn at standard test weight. Spread trailers (with wider axle spacing) may also qualify for slightly higher weight limits in some jurisdictions.
Overweight Permits During Harvest
Many states offer temporary overweight permits for agricultural commodities during harvest season, allowing gross vehicle weights well above the federal 80,000-pound limit. Some states permit loads up to 97,000 pounds or more for agricultural haulers with the right permit. At that weight, and assuming a 32,000-pound truck and trailer, you could carry roughly 1,160 bushels of 56-pound corn.
These permits vary widely by state. Some are seasonal, some require specific routes, and most come with restrictions on which roads you can use (interstates typically still enforce the 80,000-pound federal limit). Check with your state’s department of transportation before loading above standard limits, because penalties for overweight trucks can be steep.
Quick Reference for Planning Loads
- Federal weight limit (80,000 lbs gross): approximately 850 to 950 bushels, depending on truck weight
- With state harvest overweight permit: potentially 1,000 to 1,200 bushels
- Corn at 56 lbs/bu (No. 1 standard): each 1,000 lbs of payload capacity holds about 17.9 bushels
- Corn at 52 lbs/bu (high moisture): each 1,000 lbs holds about 19.2 bushels, but elevator payment is based on 56-lb market bushels
- Corn at 60 lbs/bu (low moisture, high density): each 1,000 lbs holds about 16.7 bushels, but you get credited for more market bushels at delivery
To calculate your specific load, subtract your truck and trailer’s empty weight from your legal gross weight limit, then divide the remaining pounds by your corn’s test weight per bushel. That gives you the number of bushels you can legally haul.