How the calculator works
Extension offices from North Carolina to Minnesota teach the same four-step method. We just do the arithmetic for you.
A mature horse eats about 2% of its body weight in hay each day when hay is the whole ration. For an 1,100-pound horse that's 22 pounds. Over a 150-day feeding season that is 3,300 pounds before waste. Add 5% storage loss and 13% ground-feeding waste and you're at roughly 3,900 pounds, almost two tons, or about 98 fifty-pound bales per horse.
Daily hay intake by animal
These are the defaults the calculator uses. Working animals, pregnant or nursing animals, and animals in hard cold need more; easy keepers on good pasture need less.
| Animal | Typical weight | Hay as % of body weight | Pounds per day |
|---|---|---|---|
| Horse (maintenance) | 1,100 lb | 1.5–2.5% | 17–28 |
| Pony or miniature | 600 lb | 1.5–2% | 9–12 |
| Donkey | 500 lb | 1.25–1.75% | 6–9 |
| Beef cow, dry | 1,200 lb | 2–2.5% | 24–30 |
| Beef cow, nursing | 1,200 lb | 2.5–3% | 30–36 |
| Goat | 140 lb | 3–4% | 4–6 |
| Sheep | 160 lb | 2.5–3.5% | 4–6 |
| Alpaca / llama | 150 lb | 1.25–1.75% | 2–3 |
How much hay gets wasted
University of Minnesota researchers measured how much hay horses trample, soil and refuse with different feeders. Feeding small square bales on bare ground wasted about 13%. A hay rack cut that to 5%, and a basket-style feeder to 3%. For round bales with no feeder at all, losses run 20% or more; a ring feeder brings it near 9%.
Storage matters just as much. Hay kept dry inside a barn loses about 5% to spoilage and handling. Stacked outside under a tarp on pallets, expect 10–15%. Left uncovered on the ground, a quarter of the stack can rot before you feed it.
How many days will you feed hay?
Count from when your pasture quits growing to when it comes back strong enough to carry the animals. In the Southeast that is usually November through March, about 150 days. Across the Midwest and Northeast plan on 180–210 days. If you overseed winter rye or stockpile fescue, you can trim a few weeks off.
Bale weights are not what the seller says
"Fifty-pound squares" range from 35 to 70 pounds depending on the baler, the cut and how dry it was. Round bales run anywhere from 600 to 1,500 pounds. Weigh a few bales on a bathroom scale (hold one, subtract yourself) before you trust a bale count. Buying by the ton is the only way to compare prices fairly.
Frequently asked
How many bales of hay does a horse need for winter?
Roughly 80 to 100 fifty-pound square bales for an average 1,100-pound horse over a 150-day season, once you include normal waste. Longer winters, heavier horses and ground feeding push that past 120.
How many round bales for one horse?
At 800 pounds per round bale and a 150-day season with ring-feeder waste, figure 4 to 5 bales per horse. A horse on a free-choice round bale with no ring will go through one about every 10 to 12 days.
How much hay does a cow eat per day?
A dry 1,200-pound beef cow eats 24 to 30 pounds of hay a day. Once she is nursing a calf that climbs to 30 to 36 pounds. Through a 150-day winter, a single cow needs about two and a half tons after waste.
Should I subtract grain from the hay number?
Yes, if you feed a meaningful amount. Total dry-matter intake stays near 2% of body weight, so every pound of grain displaces roughly a pound of hay. The calculator does this when you enter a grain amount.
Is it better to buy all my winter hay at once?
Usually. Late-summer and early-fall prices are lowest and the quality is best. By February supply is thin and whatever is left is often the hay nobody wanted in September.