Grain Shrink Calculator
Quantify bushel and dollar loss when drying grain to market moisture.
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
Standard empirical rule: Shrink % = (Initial moisture % − Final moisture %) × 1.2. Final bushels = initial bushels × (1 − shrink % ÷ 100). Bushels lost = initial − final. Revenue loss = bushels lost × price per bushel. The 1.2 factor approximates water removal plus normal handling loss.
Real-World Example
Corn from 25% to 15%: shrink = (25−15) × 1.2 = 12%. From 1,000 bu: final = 880 bu, loss = 120 bu. At $4.50/bu: $540 revenue loss.
Common Mistakes & Tips
Common mistakes: using simple percentage subtraction (this understates loss); forgetting that test weight often rises after drying; applying the wrong factor for soybeans or wheat; ignoring shrink on top of dockage. Compare drying cost vs wet discount to decide.
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
- UMN Extension — Grain Drying & Shrink
- USDA AMS — Grain Moisture Standards
- FAO — Grain Drying & Storage Economics
Frequently Asked Questions
What is the 1.2 shrink rule?
For every percentage point of moisture removed, bushel weight drops by about 1.2% — the extra 0.2% covers handling, broken kernels and handling losses. It is a widely used rule of thumb for marketing decisions.
Why not just subtract moisture?
Subtracting 10 points from 25%→15% suggests 10% loss. The correct formula is 11.76% (dry-matter basis), and the 1.2 rule gives 12%. The difference is the denominator: final weight is smaller, so the same water loss is a larger percentage.
Should I dry or sell wet?
Compare the on-farm drying cost (fuel + electricity + labor + equipment) with the elevator's moisture discount. If drying costs less than the discount, drying is profitable. Also consider storage time and quality.
Does the shrink factor vary by crop?
Roughly: corn uses 1.2; soybeans often use 1.3–1.4 because of their seed structure; wheat near 1.2. When in doubt, ask your elevator which formula they apply — they will tell you exactly.
What are standard target moistures?
Corn: 15% short-term, 14% long-term. Soybeans: 13%. Wheat: 13.5%. Sorghum: 14%. Storing above these raises spoilage, mold and insect risk.
