Grain Grading: How Test Weight and Damage Set Value

Two loads of corn can look the same from a truck window and still be worth different amounts. The reason is grading. Grain grades turn a handful of measured factors into a simple label that buyers and sellers can use. Understanding them helps you predict discounts and decide how to handle your crop.

Why grading exists

Before standard grades, buyers had to judge every load by eye, and disagreements were common. Grading creates a shared language. A buyer who contracts for a certain grade knows what quality to expect, and a seller knows what to deliver. In the United States, official grade standards exist for the major grains and are used as a reference in many contracts.

The main factors

Exact rules differ by crop, but several factors show up again and again.

• Test weight: the weight of a standard volume of grain, expressed in pounds per bushel. Plump, sound kernels pack more tightly and weigh more. Low test weight can signal immature, shriveled or damaged grain. This is different from the fixed trading weight of a bushel, which we covered in our explanation of what a bushel is.
• Damaged kernels: kernels hurt by heat, mold, sprouting, insects or weather. Some types of damage count more heavily than others.
• Foreign material: anything that is not the grain itself, such as weed seeds, dust, stalk pieces or stones.
• Broken kernels: for corn, the share of broken pieces and foreign material is often reported together.
• Moisture: typically not a grading factor in itself, but reported on the ticket and used to calculate discounts and shrink.

Numbered grades

Many grains are graded from number 1 downward. For corn, for instance, U.S. No. 1 requires a minimum test weight of 56 pounds per bushel, and the minimum falls with each lower grade. Grain that fails to meet the limits of the lowest numbered grade is placed in sample grade, which can be worth far less and may be refused by some buyers.

Special factors by crop

Wheat buyers often care about protein content, which affects baking quality, and about sprout damage. A common test for sprout damage is falling number. Soybean buyers look at splits, foreign material and sometimes oil and protein. Corn buyers may test for mycotoxins, which are natural toxins produced by certain molds and may limit use as feed or food.

How grades turn into dollars

Most buyers quote a bid for the base grade, for example No. 2 corn, and then publish a discount schedule. Corn below the base grade may be discounted by a set amount per bushel, and wheat may be discounted for low test weight or damage. Schedules differ between buyers, so it pays to ask.

For example, a bid of $4.70 for base-grade corn with a discount of 3 cents per bushel for a lower test weight means you would receive $4.67 per bushel. Multiplied across a 1,000 bushel load, the discount costs $30.

Ways to protect quality

1. Adjust combine settings to reduce broken kernels and cracked beans.
2. Clean grain before delivery if the buyer's schedule penalizes foreign material.
3. Dry and store grain properly to avoid heat damage and mold.
4. Keep samples and records, so you can compare against the elevator's results.
5. Ask for a re-test or an official inspection if you disagree with a grade.

Seeing it in action

Grading happens at the probe stage in the receiving process. You can read about how that fits into the whole system in our guide on how a grain elevator works.

Frequently asked questions

Who sets grain grades? In the United States, official standards exist through federal grain inspection rules. Buyers often add their own contract terms, so check what your buyer uses.

Can I appeal a grade? Usually yes. You can ask for another sample or request official inspection services, though the process may cost money and take time.

Does a lower grade mean the grain is unsafe? Not necessarily. Grades describe quality for trading. Safety concerns, such as toxins, are tested separately.