How Much Hay Does a Cow Eat per Day? (By Weight, With Waste)
A cow eats about 2.5% of her body weight in hay a day when hay is all she gets. That is about 25 lb for a 1,000 lb cow and 30 lb for a 1,200 lb cow. Add 10–25% for waste, depending on how you feed it, so plan on buying about 33–38 lb a day for a 1,200 lb cow.
Hay per day by cow weight
| Cow weight | Hay eaten per day (2.5%) | To buy, with 15% waste | Per 150-day winter, with 15% waste |
|---|---|---|---|
| 800 lb | about 20 lb | about 23.5 lb | about 3,530 lb (1.8 tons) |
| 1,000 lb | about 25 lb | about 29.4 lb | about 4,410 lb (2.2 tons) |
| 1,200 lb | about 30 lb | about 35.3 lb | about 5,290 lb (2.6 tons) |
| 1,400 lb | about 35 lb | about 41.2 lb | about 6,180 lb (3.1 tons) |
Where the 2.5% comes from
Cattle eat a fairly steady share of their body weight each day. On average-quality hay, a mature beef cow eats roughly 2–2.5% of her weight on a dry-matter basis, and because hay is only about 85–90% dry matter, 2.5% as fed is a practical planning number. It is a little generous for a dry cow on average hay, which is what you want when buying hay for a whole winter.
What makes a cow eat more or less
- Hay quality. Cows eat more of soft, leafy, early-cut hay and less of coarse, stemmy, late-cut hay, because coarse hay takes longer to digest and keeps the rumen full.
- Stage. A cow nursing a calf eats more than a dry, pregnant cow, often closer to 3% of her body weight. Growing heifers and steers also eat at the high end.
- Cold. In cold, wet or windy weather cattle eat more to stay warm. Plan extra hay for a hard winter.
- Other feed. Pasture, grain or a protein supplement replaces some hay, so cattle on stockpiled grass or cornstalks for part of the winter need far less.
How long does a round bale last?
A 4×5 round bale often weighs about 800 lb. Ten 1,200 lb cows eat about 300 lb of hay a day, and with 15% waste a bale gives about 680 lb of eaten hay, so one bale lasts about 2 days. One cow alone would take about 3 weeks to finish it, too long in wet weather, so a single cow or a small herd is easier to feed from small squares or a covered feeder.
How much hay per cow for the winter?
A 1,200 lb cow fed for a 150-day winter eats about 4,500 lb of hay. With 15% waste you need to buy about 5,290 lb, roughly 7 round bales of 800 lb or 106 small squares of 50 lb. Buy 10–20% more than that if your winters run long, since running out in March costs far more than a few leftover bales.
Cut the waste and the hay goes further
Waste is the number most people underestimate. Unrolling or feeding hay on the ground can waste 25% or more as cattle trample, lie on and soil it. A round bale feeder with a ring or cone, or feeding only a day or two's worth at a time, can bring waste down to about 5–15%. Storing bales off the ground and under cover also prevents the spoiled outer layer that cattle refuse to eat.
Use the hay calculator below with your own herd size, cow weight, bale size and days of feeding to get bales, tons and cost.
Common questions
How much hay does a cow eat in a day?
About 2.5% of her body weight on a hay-only diet: about 25 lb for a 1,000 lb cow and about 30 lb for a 1,200 lb cow. Nursing cows and cattle in cold weather eat more.
How many round bales does a cow need for winter?
About 7 round bales of 800 lb for a 1,200 lb cow over a 150-day winter, with 15% waste. Larger bales, less waste or a shorter hay season need fewer.
Figures are typical values from university extension and breed-association guidance. Estimates only. Individual animals vary — confirm pregnancy and health questions with your veterinarian.