Grain Drying Calculator
Moisture points to shrink and dry bushels.
What it does
Drying corn trades water weight for storage life. Each point of moisture removed shrinks the load about 1.4 %, so a thousand wet bushels never fill a thousand dry ones. Points times shrink previews the bin.
The tool above subtracts end moisture from start for points, multiplies by corn's 1.4 % shrink factor, and reduces the bushels. It prints points removed, shrink percent, and dry bushels ready to store.
Extension grain handling guides and elevator shrink tables teach this same points-times-factor method with 15 % as corn's storage target. Dry matter stays while water leaves, which is why the bushel count falls even as quality rises.
Dry to target before binning, cool hot grain, and move it gently. Overdrying burns test weight and cracks kernels; wet binning grows mold and heat. The math sets expectations; meters and thermometers run the dryer.
How to use
- Enter start moisture percent.
- Enter target moisture percent.
- Enter wet bushels.
- Read points, shrink, and dry bushels.
- Dry to 15 % before binning corn.
- Handle hot grain gently.
Formula
- start
- Incoming grain moisture percent.
- end
- Target storage moisture percent.
- bushels
- Wet bushels into the dryer.
Start and end are wet-basis moisture percents with start above end. The 1.4 % shrink factor is corn's standard moisture-shrink figure; dry-matter loss and handling add their own smaller cuts.
Worked example
Example: 22 % to 15 %, 1000 bu
1000 bushels of corn from 22 % down to 15 %.
- Wet corn at 22 %, target 15 %, 1000 bu.
- Points removed: 22 - 15 = 7 points.
- Shrink: 7 x 1.4 % = 9.8 %.
- Dry bushels: 1000 x (1 - 0.098) = 902 bu.
- Handle hot grain gently out of the dryer.
Reference table
| Points | Shrink | 1000 bu becomes |
|---|---|---|
| 3 | 4.2 % | 958 bu |
| 5 | 7.0 % | 930 bu |
| 7 | 9.8 % | 902 bu |
| 10 | 14.0 % | 860 bu |
| 13 | 18.2 % | 818 bu |
Limits
- Corn shrink factor. Other grains differ slightly.
- Moisture shrink only; handling loss adds more.
- Meter error swings points both ways.
- Storage target varies by season and bin.
Common mistakes
- Binning wet and hoping air fixes it.
- Confusing points with percent of crop.
- Skipping test weight after drying.
- Moving hot grain roughly.
- Storing at 15 % for summer holds.
Try it yourself
Quick checks. Answers sit tucked under each question.
1000 bu from 28 % to 15 %?
Points are 28 - 15 = 13. Shrink is 13 x 1.4 = 18.2 %. Dry is 1000 x 0.818 = 818 bu.
500 bu from 20 % to 15 %?
Points are 20 - 15 = 5. Shrink is 5 x 1.4 = 7 %. Dry is 500 x 0.93 = 465 bu.
Questions
What is a point of moisture?
Points of moisture removed: start percent minus end percent. Each point evaporates water weight, so bushels shrink even though kernels stay.
How much shrink per point?
About 1.4 % of weight per point for corn, the standard shrink factor elevators apply. Soybeans and wheat run nearby with their own tables; this page uses corn's 1.4.
What moisture stores safely?
15 % for stored corn (13 to 14 for long summer holds). Wet grain heats and molds fast; dry to target before binning, not after.
Do dry bushels weigh less per bushel?
Dry bushels times test weight math: water leaves, dry matter stays. A 1000-bu load at 22 % becomes 902 at 15 %; the elevator dries, shrinks, then charges both.
Why handle dry grain gently?
Hot, brittle grain cracks in legs and augers. Cool it, move it gently, and core the bin after filling so fines never center-spout.
What does overdrying cost?
High-temp yellowing, stress cracks, and test-weight loss. Dryer heat buys speed with quality; in-bin air buys quality with time.