Test Weight Deduction Calculator
Estimate the penalty for grain below standard test weight.
Results
How to Use This Calculator
Enter the required input values in the form fields above. Each field includes default values that you can adjust to match your specific situation. Click the Calculate button (or simply change any input) to see instant results. Use the Metric/Imperial toggle to switch between unit systems. Results are displayed in the results panel and can be used for farm planning and decision-making.
About This Tool
This calculator is designed to help farmers, agronomists, and agricultural students make quick, accurate calculations for farm management. It uses standard agricultural formulas based on extension service recommendations and scientific literature. Whether you are planning inputs, estimating yields, or managing finances, this tool provides reliable estimates to support your decisions.
Applicability: Relevant for grain storage operations in North America and Europe.
How the Calculation Works
Deficit = standard test weight − actual test weight (lb/bu). Discount % = deficit ÷ standard test weight. Bushels deducted = delivered bushels × discount %. Dollar deduction = bushels deducted × deduction rate per bushel. Typical standards: corn No. 1 = 56 lb/bu, No. 2 = 54, No. 3 = 52.
Real-World Example
53 lb/bu actual vs 56 standard on 5,000 bu: deficit = 3 lb/bu, discount = 5.36%, bushels deducted = 268. At $0.30/bu: $80.40 deduction.
Common Mistakes & Tips
Common mistakes: comparing to the wrong standard (commodity-specific); using a flat 0.5 lb step when the proportional formula is more accurate; forgetting that low test weight also correlates with high moisture; not re-testing after drying.
Reviewed by Agricalc Editorial Team — Agricultural engineers and agronomists with 10+ years of field experience. Our team verifies every calculator formula against peer-reviewed extension publications. For site-specific advice, consult your local agronomist.
References
- USDA AMS — Grain Grade & Test Weight Standards
- UMN Extension — Grain Grading & Discounts
- FAO — Grain Quality Standards
Frequently Asked Questions
What test weight makes No. 2 corn?
USDA No. 2 corn requires 54 lb/bu minimum; No. 1 is 56 lb/bu. Each 2 lb drop is a grade. Below 52 lb/bu grain is No. 3 or lower and faces steep discounts.
Does drying improve test weight?
Often, yes. As grain dries it settles and kernels pack more densely, raising test weight by 0.5–2 lb/bu. Re-test after drying before selling.
Why is low test weight penalized?
Lower test weight means less grain density per volume. Elevators sell by weight, so a bushel that weighs less costs them storage, transport and handling. They pass that cost on via discounts.
What causes low test weight?
Drought stress, frost before maturity, high nitrogen with low stand, thin kernel filling, and harvesting too early. It is a quality signal, not just a number.
Should I wait for better test weight?
Compare storage costs and market price with the discount. Sometimes paying the discount and selling now beats storing, drying, and risking further quality loss.
