Hay & Forage Calculator

Frequently Asked Questions

How much hay does a cow eat per day?

A mature cow eats about 2 to 2.5% of its body weight in dry hay daily, so a 1,200-lb cow needs roughly 24 to 30 lb per day before waste.

Why add a waste allowance?

Hay fed on the ground or in poor feeders is trampled, fouled, and refused. A 15% allowance is typical; ground-fed round bales can lose 30 to 40%.

How many pounds is a bale of hay?

Small square bales average about 50 lb and round bales about 1,000 lb, but moisture and size vary widely, so weigh a sample for accuracy.

How can I reduce hay waste?

Use a hay ring or cone feeder, feed only what is cleaned up in a day, and keep hay off wet ground. This can roughly halve feeding waste.

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This calculator provides estimates for informational purposes only. Results are based on assumptions and may not reflect actual outcomes. Consult qualified professionals in relevant fields before making important decisions based on these results.

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How This Calculator Works

Running out of hay in February is a real and expensive problem, so the safe move is to size your winter supply before the season starts. Forage intake scales with body weight: a horse or cow eats roughly 2–2.5% of its body weight in dry hay per day, so a herd's daily demand is simply head count times average weight times that percentage. This calculator multiplies that daily figure by the number of feeding days, then adds a waste allowance because hay fed on the ground, in poorly designed feeders, or left to weather is trampled and refused - commonly 15% and often much higher with round bales fed without a ring. It then translates the total into tons and into both small square bales and large round bales so you can plan storage, transport, and how many to buy or cut.

Formula / Method

Daily intake (lb) = animals × average weight (lb) × (body-weight % ÷ 100). Total hay (lb) = daily intake × days × (1 + waste % ÷ 100). Tons = total lb ÷ 2,000. Small square bales = ceiling(total lb ÷ 50), assuming a 50 lb bale; round bales = ceiling(total lb ÷ 1,000), assuming a 1,000 lb bale. Bale weights vary widely, so treat the bale counts as planning estimates and weigh a sample if precision matters. Default intake is 2.5% and default waste 15%; both are editable. Non-positive animals, weight, or days are rejected.

Worked Example

Ten cows averaging 1,200 lb, fed 2.5% of body weight for 120 winter days, with 15% feeding waste. Daily intake = 10 × 1,200 × 0.025 = 300 lb. Total before waste = 300 × 120 = 36,000 lb; with 15% waste = 41,400 lb, or about 20.7 tons. That is roughly 828 fifty-pound squares or 42 thousand-pound rounds. Cut waste to 5% with a good feeder and you save nearly four tons over the winter.

Common Mistakes

Forgetting the waste allowance entirely - ground-fed round bales can lose 30–40%, not the tidy 15% default.

Using as-fed intake percentages against dry-matter targets, or vice versa, double-counting moisture.

Assuming every round bale weighs 1,000 lb; moisture and size push real bales anywhere from 600 to 1,500 lb.

Ignoring that lactating, growing, or cold-stressed animals eat well above the maintenance percentage.

Buying exactly the calculated amount with no buffer for a long winter, spoilage, or a late spring green-up.

Tips & FAQ

What intake percentage should I use? About 2% of body weight for mature idle animals on good hay, 2.5–3% for growing, lactating, or cold-stressed stock. How do I cut waste? Use a hay ring or cone feeder for round bales, feed only what is cleaned up in a day, and keep hay off wet ground - this single change can halve your waste line. Should I weigh my bales? Yes if you can; bale weight is the biggest source of error, and a bathroom-scale spot check beats a guess. Why plan for extra days? Winters run long and pastures green up late, so adding two or three weeks of feeding days is cheap insurance against a frantic, overpriced hay hunt in March.

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