Hay Calculator: How Many Bales per Horse or Cow
Grazing animals eat a share of their body weight in hay each day. Enter body weight, the intake percentage, a waste allowance, the number of days and your bale weight to find the hay needed and the bales to buy. The intake and waste figures are typical values and vary with the animal, the hay quality and the feeding method, so adjust them for your own herd.
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Formula
- Hay per animal per day =
body weight x intake % x (1 + waste %) - Total hay =
hay per animal per day x animals x days - Bales needed =
total hay / bale weight, rounded up
Intake (about 1.5% to 3% of body weight, 2% by default) and waste (5% to 20%, 10% by default) are typical values, not fixed rules. Intake is treated as weight of hay as fed.
Worked example
Two 1,000 lb animals, 2% intake, 10% waste, 30 days, 50 lb bales:
- Per animal per day: 1,000 x 0.02 x 1.10 = 22 lb
- Both animals: 44 lb a day, 1,320 lb over 30 days
- Bales: 1,320 / 50 = 26.4, so 27 bales
Round bale case: one 1,200 lb cow, 2.5% intake, 20% waste, 120 days, 1,000 lb bales: 36 lb a day, 4,320 lb, so 5 bales.
Metric check: three 450 kg animals, 2.5% intake, 15% waste, 90 days, 20 kg bales need 3,493.13 kg, or 175 bales.
When to use it
Use it to budget hay for a winter, to compare buying small square bales with large round bales, or to see how a different waste allowance changes your order. A slow feeder or net usually wastes less than feeding on the ground.
Common mistakes
- Using bale weights from memory. Bales of the same size can vary widely in weight, so weigh a few.
- Forgetting the waste allowance, then running out before spring.
- Using a single intake percentage for animals with very different needs, such as a working horse and a retired pony.
How it differs from nearby calculators
The stocking rate calculator asks how many animals your land can carry on pasture, while this one prices out the hay once animals are fed. The chicken feed calculator covers bagged poultry feed instead of forage. For advice on a specific animal, ask a vet or nutritionist.
Frequently asked questions
How much hay does a horse eat per day?
A common rule of thumb is about 2% of body weight in hay per day. For a 1,000 lb horse that is 20 lb, or 22 lb once you add 10% for waste. Needs rise with work, cold weather and lactation, and fall with good pasture.
How do I work out how many bales I need?
Multiply hay per animal per day by the number of animals and the days, then divide by the bale weight and round up. Two 1,000 lb horses at 2% intake and 10% waste for 30 days need 22 x 2 x 30 = 1,320 lb, which is 26.4 bales of 50 lb, so buy 27.
What waste factor should I use?
Waste depends on how you feed. Hay fed in a feeder or net often loses 5% to 10%, while hay fed on the ground or in an open round-bale ring can lose 20% or more. The default of 10% is a typical value, so change it to match your setup.
Can I use this for cattle, sheep and goats?
Yes, as a starting estimate. Enter the average body weight and an intake percentage for the animal and hay quality, because typical values range from about 1.5% to 3% of body weight. For specific feeding advice, ask a vet or nutritionist.
How many 50 lb bales of hay does a horse need per month?
A 1,000 lb horse at 2 percent intake with 10 percent waste eats 22 lb a day, which is 660 lb over 30 days. Divided by 50 lb bales that is 13.2, so buy 14 bales.
How much hay does a 1,000 lb cow eat per day?
Cattle commonly eat about 2.5 percent of body weight in hay, a typical figure. For a 1,000 lb cow with 10 percent waste that is 1,000 x 0.025 x 1.10 = 27.5 lb a day.
How many round bales does a cow need for 120 days?
A 1,200 lb cow at 2.5 percent intake with 20 percent waste eats 36 lb a day, or 4,320 lb over 120 days. With 1,000 lb round bales that is 4.32, so plan for 5 bales.