AgricultureID

Calculator · post-harvest

Grain moisture shrink calculator

Calculates the mathematical moisture shrink between a starting moisture and a market moisture — the water fraction alone.

Grain is commonly traded on the wet basis, but nothing here assumes it for you.

Leave blank unless you are carrying a figure from your own contract. It is echoed back separately and is never folded into the mathematical shrink.

Result

Choose the moisture basis your figures are denominated on. 20% wet basis and 20% dry basis are different quantities.

Formula & assumptions

Mathematical moisture shrink

formula v1.0.0 · calc v1 · reviewed 2026-07-16

Shrink% = (M₀_wb − M₁_wb) ÷ (100 − M₁_wb) × 100

Applies to: Grain and oilseed traded against a stated market moisture.

Assumptions

  • Dry matter is conserved. This is the mass fraction lost as water alone — it is drying-water-removed expressed as a percentage of the starting mass.

Limitations

  • MATHEMATICAL shrink only. It is not handling shrink, not a commercial shrink factor, and not a total elevator deduction — those are commercial policies that vary by buyer, contract, and jurisdiction, and this platform does not publish them as universal.
  • A buyer’s actual deduction commonly exceeds this figure, because it may add handling loss and a commercial factor on top. The difference is a contract term, not arithmetic.

Scope

Not a settlement calculation and not a contract term. It computes the water fraction only; what a buyer actually deducts is set by that buyer’s contract.

Sources: USDA Economic Research Service (ERS) (opens in a new tab), Iowa State University Extension and Outreach (opens in a new tab), University of Minnesota Extension (opens in a new tab)

Moisture: dry basis → wet basis

formula v1.0.0 · calc v1 · reviewed 2026-07-16

M_wb = M_db ÷ (100 + M_db) × 100

Applies to: Any commodity whose moisture is reported on a stated basis.

Assumptions

  • Water and dry matter are the only components; nothing else is present or is being tracked.

Limitations

  • A conversion between two denominators, not a measurement.
  • The result approaches but never reaches 100%, which is the definitional ceiling of wet basis.

Scope

Arithmetic on the numbers entered. It does not replace representative sampling or a calibrated, correctly-referenced moisture meter, and it cannot detect that an input was wrong.

Sources: Food and Agriculture Organization of the United Nations (FAO) (opens in a new tab), USDA Agricultural Research Service (ARS) (opens in a new tab)

About this tool

  • Mathematical shrink only: the mass fraction that leaves as water. It is not handling shrink, not a commercial shrink factor, and not a total buyer deduction.
  • A buyer’s actual deduction commonly exceeds this figure because it may add handling loss and a commercial factor on top. That difference is a contract term, not arithmetic.
  • This platform publishes no commercial shrink factor. Any figure in the optional field is yours, carried from your own contract, and this tool neither supplies nor checks it.

Educational reference — not a prescription

Not a settlement calculation and not a contract term. It computes the water fraction only; what a buyer actually deducts is set by that buyer’s contract, and no figure here establishes what any buyer owes or deducts.

  • These calculators are for education and reference. The quality of any result depends entirely on the accuracy of the values you enter.
  • Local agronomic conditions, legal requirements, product labels, and professional advice may override a general calculation.
  • Results are not pesticide, fertilizer, irrigation, or veterinary prescriptions, and are not a substitute for advice from a qualified agronomist or your local extension service.