Grain shrink calculator
This grain shrink calculator shows how much weight grain loses in the dryer: 1,000 lb of corn at 25 % moisture weighs 887.6 lb at 15.5 %, or 882.6 lb with the usual 0.5 % handling loss. It gives water shrink, total shrink and dry weight.
Example: Weight before drying 1,000 · Unit: lb · Moisture before 25 % · Moisture after (target) 15.5 % · Method: Water shrink + handling loss (drying table) · Handling loss 0.5 % → After drying: After drying: 882.6 lb (shrink 11.74 %). Source: D. R. Hicks, H. A. Cloud: Calculating Grain Weight Shrinkage in Corn Due to Mechanical Drying, National Corn Handbook NCH-61 (1992/2001) – p. 1 example 25 % → 15.5 % = 11.24 %, p. 2 Water Shrink Factor = 100 ÷ (100 − final moisture), Table 1, method 1 (+0.5 % handling) and method 2 (1.2–1.5 % per point), Iowa State values 0.22–1.71 % (read 10.10.2026). Updated: .
How it is calculated
Water shrink (%) = (moisture before − moisture after) ÷ (100 − moisture after) × 100. Drying removes only water; the dry matter stays. Example from the National Corn Handbook (NCH-61, University of Minnesota): 1,000 lb of corn at 25 % moisture holds 750 lb of dry matter. At 15.5 % moisture that dry matter is 84.5 % of the new weight, so 750 ÷ 0.845 = 887.57 lb. 112.43 lb of water was removed – a water shrink of 11.24 %.
Water shrink factor per point
Dividing shrink by the points of moisture removed gives the water shrink factor = 100 ÷ (100 − final moisture). It depends only on the target moisture:
| Final moisture | Shrink factor per point | Water shrink from 25 % |
|---|---|---|
| 15.5 % | 1.183 % | 11.24 % |
| 15 % | 1.176 % | 11.76 % |
| 14 % | 1.163 % | 12.79 % |
| 13 % | 1.149 % | 13.79 % |
| 12 % | 1.136 % | 14.77 % |
Handling loss and constant shrink factors
Besides water, drying loses some dry matter through broken kernels, fines and volatile compounds. According to NCH-61, drying tables usually add 0.5 % of the initial weight: 11.24 % + 0.5 % = 11.74 % total shrink, so 1,000 lb becomes 882.6 lb. Iowa State University research measured 0.22 to 1.71 % on farms and 0.64 to 1.33 % in commercial dryers.
Instead of drying tables, buyers may use a constant shrink factor per point; NCH-61 gives 1.2 to 1.5 % as typical. At 1.3 %, 9.5 points give 12.35 % shrink; 11.24 % of that is water, and the remaining 1.11 % is an assumed handling loss. NCH-61 notes there is no standard method for this “pencil shrink”, so comparing quotes pays off.
For other percentage questions use the percentage calculator; to switch between pounds and kilograms use kg to lbs.
Frequently asked questions
How do you calculate grain shrink?
(Moisture before − moisture after) ÷ (100 − moisture after) × 100. From 25 % to 15.5 % that is 11.24 % of the original weight.
What is the shrink factor for corn at 15.5 %?
1.183 % per point of moisture removed, from 100 ÷ (100 − 15.5). At 14 % it is 1.163 % and at 12 % it is 1.136 %.
What is handling loss in grain drying?
Dry matter lost to broken kernels, foreign material, volatile compounds and possibly respiration. Drying tables usually add 0.5 %; Iowa State measured 0.22 to 1.71 % on farms.
Why does my elevator use 1.3 % per point?
A constant factor includes water shrink plus an allowance. From 25 % to 15.5 % it gives 12.35 % instead of 11.74 % with water shrink and 0.5 % handling loss.
Does the formula work for wheat or soybeans?
The mass balance works for any grain as long as moisture is stated on a wet basis. The examples in NCH-61 are for shelled corn.
Sources and legal basis
As of: · Editorial policy
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