How to use the hay calculator
- Add a row for each group of animals: the type, how many, and their average weight. Leave “% body weight” blank to use a typical figure, or enter your own.
- Enter the days to feed hay — the time from when pasture runs out until spring grass is ready.
- Set the waste for how you feed it, choose the bale type (or enter your bale weight) and, optionally, the price per bale.
The formula
Hay per day = Σ (animals × weight × % body weight) Hay to buy = Hay per day × days × (1 + waste %) Bales = Hay to buy ÷ bale weight → round up
Worked example
Two 1,100 lb horses at 2% body weight, fed for 150 days with 15% waste in 50 lb bales:
- Per day = 2 × 1,100 × 0.02 = 44 lb
- Hay to buy = 44 × 150 × 1.15 = 7,590 lb (about 3.8 US tons)
- Bales = 7,590 ÷ 50 = 152 small square bales
Typical daily hay intake
| Animal | Typical weight | % body weight per day | Hay per day |
|---|---|---|---|
| Horse | 1,100 lb (500 kg) | 1.5–2.5% | about 22 lb (10 kg) |
| Pony / miniature | 500 lb (225 kg) | 1.5–2.5% | about 10 lb (4.5 kg) |
| Beef cow | 1,300 lb (590 kg) | 2–2.5% | about 30 lb (14 kg) |
| Goat | 150 lb (68 kg) | 3–4% | about 5 lb (2.4 kg) |
| Sheep | 160 lb (73 kg) | 2.5–3.5% | about 5 lb (2.2 kg) |
| Alpaca / llama | 150 lb (68 kg) | 1.5–2% | about 2.6 lb (1.2 kg) |
| Donkey | 400 lb (180 kg) | 1.5–2% | about 7 lb (3.2 kg) |
These are planning figures for hay as the main forage. Pregnant, lactating, growing and working animals eat more; animals with access to winter pasture or other feeds eat less. Ask your vet or extension service for a ration for your animals.
Bale weights
Bale weight varies with the baler, the crop and its moisture, so the best figure is your own. Weigh three or four bales on a bathroom or livestock scale and use the average. As a guide, small square bales are often 40–70 lb, large three-string squares 100–130 lb, 4 × 4 ft round bales around 500–600 lb, 5 × 5 ft rounds 800–1,000 lb, and big 3 × 4 × 8 ft squares 800–1,000 lb.
Ways to cut hay waste
- Use a feeder: slow-feed nets, cone or ring feeders for round bales and covered racks all reduce trampled hay.
- Feed little and often: animals waste less when they get only what they will eat in a day.
- Store hay dry: keep bales under cover and off the ground on pallets. Round bales stored outside uncovered can lose a large share of their outer layer.
- Buy good hay: animals refuse dusty, moldy or very stemmy hay. A forage test tells you the protein and energy so you can balance the ration.