Home › Hay needs calculator

Winter Hay Needs Calculator for Cattle

Estimate how many tons and bales of hay your herd needs to get through winter. It runs in your browser, is free, and needs no signup.

How the math works

1. Dry matter intake = body weight × 2.5%. Extension services use 2.5% of body weight as a planning estimate for a cow's daily forage dry matter intake; lactating cows, cold weather and better hay can push it higher.
2. As-fed hay = dry matter ÷ hay dry matter %. If you haven't tested your hay, 85–90% dry matter is a common starting estimate.
3. Add losses. Hay stored outside can lose 20% or more; inside, around 7%. Feeding in bunks can waste 3–14%, and unrolling several days' worth on the ground can waste up to 45%.
4. Total = per-cow hay × head × days ÷ 2,000 for tons, or ÷ bale weight for bales. Weigh a few bales; guessing bale weight is the biggest source of error.

A familiar shortcut from Illinois Extension: a 1,300 lb cow eating free choice uses about one big round bale a month.

This is a planning estimate, not a ration. It assumes hay is the whole diet and that its quality meets the herd's needs. For a balanced ration, test your hay and talk with your county Extension agent or nutritionist.

Sources

• NDSU Extension: take stock of your forage supply before winter feeding (2.5% intake, 85–90% DM, storage and feeding losses)
• University of Wisconsin Extension: determining winter feed needs (as-fed conversion, 4–50% losses)
• UF/IFAS AN244: Winter Feed Estimator for the cow-calf producer
• Illinois Extension: budgeting feed needs for the winter

Related: hay moisture testers · hay and feed tools · free cattle record template

Get the next free tool

We're building more free calculators (stocking rate is next). Get them in The Ranch Stack Weekly, one short email a week.