What grain shrink is
Grain is bought and sold at a standard moisture, for example 15.5% for corn and 13% for soybeans in the United States. Grain harvested wetter must be dried, and the weight lost is called shrink. There are two parts: water shrink, the water removed, and handling shrink, the dust, broken kernels and fines lost along the way.
The formula
The dry matter does not change during drying, so:
Dry weight = wet weight × (100 − harvest moisture) ÷ (100 − target moisture)
The calculator then removes the handling shrink, often 0.5% to 1%.
Example
10,000 bushels of corn harvested at 22% and dried to 15.5%, with 0.5% handling shrink:
- water shrink: 10,000 × 78 ÷ 84.5 ≈ 9,231 bu;
- after handling shrink: about 9,185 bu;
- total shrink: about 8.2%;
- at $0.04 per point per bushel, drying 6.5 points costs about $2,600.
Shrink per point
Removing one point of moisture costs more than 1% of the weight, because the remaining grain is lighter too:
Water shrink per point = 100 ÷ (100 − target moisture)
At 15.5%, that is 1.183% per point. Elevators often use a slightly higher figure, such as 1.3% or 1.4% per point, which includes their own handling shrink. Compare their schedule with the true water shrink before deciding whether to dry on the farm.
Common market moistures
| Crop | Standard moisture |
|---|---|
| Corn | 15.5% |
| Soybeans | 13% |
| Wheat | 13.5% |
| Sorghum | 14% |
| Sunflower | 10% |
Drying decisions
- Field drying is free but risks lodging, ear drop, stalk rot, wildlife damage and a late harvest. Corn often dries 0.5 to 1 point per day in early fall, much less later.
- On-farm drying costs fuel and electricity: about 0.02 to 0.03 gallons of propane per bushel per point in a high-temperature dryer.
- Storage moisture matters as much as market moisture: corn stored into summer is safer at 14% or lower.
Tips
- Sample moisture from several loads with a calibrated meter.
- Do not over-dry: grain dried below the market standard is sold at a lower weight with no premium.
- Cool grain promptly after drying and aerate the bin to prevent hot spots.