Grain Test Weight & Bushel Calculator (Weight vs Volume Bushels, Discounts)
Turn scale-ticket pounds or kilograms into bushels for corn, soybeans, wheat, oats, barley, sorghum, rye and sunflower at their standard bushel weights, convert bin, truck-box or wagon volume to weight bushels with the measured test weight (lb/bu or kg/hL), see the USDA grade the test weight makes, moisture shrink and the dried test weight, and the discount and net value at your elevator’s schedule.
How it works
weight bushels = pounds ÷ standard weight (corn 56, soybeans & wheat 60, oats 32, barley 48) · volume bushels = ft³ ÷ 1.2445 (or m³ ÷ 0.03524) · weight in a bin = volume bushels × test weight · kg/hL = lb/bu × 1.2872 · water shrink = 1 − (100 − wet) ÷ (100 − base) · dried test weight ≈ test weight × (100 − base) ÷ (100 − wet) · discount = (threshold − test weight) × $/lb × paid bushels
A bushel is legally a volume — about one and a quarter cubic feet (35.24 litres) — but grain is traded by weight at a fixed number of pounds per bushel for each crop, so the scale ticket, not the truck box, decides the payment. Test weight, the pounds an actual bushel volume of the sample weighs, links the two: light grain fills bins and trucks with fewer paid bushels and, below the grade minimums, draws a discount because it usually signals immature or damaged kernels. Enter the scale weight (lb, kg or tonnes), a volume, or the inside dimensions of a truck box or wagon, and the measured test weight in lb/bu or kg/hL. The calculator shows weight and volume bushels, the U.S. grade the test weight alone makes (for soybeans test weight has been informational only since 2007), and the discount and net value at your buyer’s schedule, including an optional steeper second tier. Under More options, enter the delivery moisture to see the moisture shrink and the test weight the grain may reach once dried. Drying, cleaning and the season’s growing conditions all shift test weight by a few pounds, which is worth knowing before the sample is pulled.
Worked example
A 52,000 lb net load of corn is 929 weight bushels whatever it tests; at 54 lb/bu (69.5 kg/hL) it fills about 963 volume bushels, so a bin rated 10,000 bushels holds only about 9,640 of this corn. At 54 it makes U.S. No. 2 with no discount and is worth $4,179 at $4.50. Had it tested 51 (No. 4), a 2¢ per pound schedule would take 6¢ a bushel — about $56 off the load. Delivered at 20% moisture against a 15.5% base, water shrink is 1 − 80 ÷ 84.5 = 5.33%, leaving 880 paid bushels, and the corn could test up to about 57 lb/bu once dried.
Sources: Ohio State University — Corn grain test weight (grade minimums, drying formula) · Ohio State University Extension — Grain test weight (AGF-503) · farmdoc (University of Illinois) — Wet grain, test weight and late harvest · Federal Register (2006) — Soybean test weight made informational
Frequently asked questions
Does high test weight mean higher yield?
Not directly — yield is weight per acre and test weight is density. They often move together because well-filled kernels are both heavier and denser, but a bin of 58 lb corn and 54 lb corn from the same scale weight is the same number of paid bushels.
Why does my yield monitor bushel differ from the elevator?
Monitors estimate weight from flow and convert at the standard bushel weight and a set moisture; the elevator pays on scale weight, shrunk to standard moisture, with its own shrink factor. Calibrate the monitor with a weighed load and expect a few percent difference.
What are the minimum test weights for each grade?
Under the U.S. grain standards: corn No. 1 56, No. 2 54, No. 3 52, No. 4 49, No. 5 46 lb/bu; most wheat classes 60, 58, 56, 54, 51 (hard red spring and white club 58, 57, 55, 53, 50); oats 36, 33, 30, 27; barley 47, 45, 43, 40, 36; sorghum 57, 55, 53, 51. Soybean test weight is informational only.
How do I convert lb/bu to kg/hL?
Multiply by 1.287: 54 lb/bu is 69.5 kg/hL and 60 lb/bu is 77.2 kg/hL. You can enter the test weight in either unit.
How much does drying change test weight?
Test weight usually rises as wet corn dries, because the kernels shrink and pack tighter. The extension formula test weight × (100 − dry %) ÷ (100 − wet %) gives an upper estimate — 52 lb/bu at 25% becomes up to 58.9 at 15% — while drying trials typically find about 0.5–0.7 lb/bu per point removed.
Related calculators
Agronomic rules of thumb and standard grain-trade formulas from extension services. Local elevators, labs and equipment dealers publish their own schedules and specifications — use those where they differ, and confirm lime and fertilizer rates with a current soil test.