Horse Hay Calculator
How much hay a horse eats a day and how many bales to buy for the winter or any number of days, with storage and feeding waste allowed for.
Result
Bales to buy: 67 balesEstimate
Rounded up to whole bales, with both wastes includedStorage and feeding waste are included. The share of body weight is a starting figure: body condition and your vet’s advice come first.
- Hay to buy
- 2,668.1 lb (1.3 ton)Estimate
- Hay eaten per day, all horses
- 20 lb (9.1 kg)Estimate
- Hay eaten over the days, before waste
- 2,420 lb (1.2 ton)Estimate
- Bales used per week
- 3.9Estimate
https://calcgallery.com/pets/horse-hay-calculator/
Results are arithmetic on the figures you enter and are estimates. Products, materials and animals vary, so follow the maker's instructions and label, make a test piece where it matters, and ask a vet about feeding. Nothing here is safety or veterinary advice. Read the full disclaimer
How to use the Horse Hay Calculator
- Enter the body weight of each horse and how many horses you feed.
- Check the share of body weight. It starts at 2%, University of Maryland Extension's figure; use the figure your vet or nutritionist gives if you have one.
- Enter the days to feed and the weight of one of your bales.
- Adjust the storage and feeding waste to how you store and feed hay.
- Read the bales to buy, and add the flake count and price per bale if you want flakes a day and the cost.
How it is calculated
eaten a day = body weight × share of body weight × horsesfed a day = eaten a day × (1 + feeding waste)bought a day = fed a day × (1 + storage waste)bales = ⌈bought a day × days ÷ bale weight⌉flakes a day = fed a day ÷ (bale weight ÷ flakes in a bale)The 2% share and the two 5% wastes are from the University of Maryland Extension article “Calculating Your Horse’s Winter Hay Needs”. The article multiplies by 1.05 for storage and 1.05 for feeding, and its 67-bale example is one of this page’s tests.
Weigh, do not guess
Two numbers carry most of the error: the horse’s weight and the bale’s. A weight tape or a scale at a clinic beats an estimate by eye, and bales of the same size can differ by 10 lb or more depending on how tightly they were baled and how dry the hay is. Weigh a few of your bales and use the average. Check your horse’s body condition through the winter coat as the season goes on, and adjust.
With your numbers
- Eaten a day = 1,000 lb × 2% × 1 = 20 lb
- Hay to buy = eaten a day × (1 + 5%) × (1 + 5%) × 121 days = 2,668.1 lb
- Bales = ⌈2,668.1 lb ÷ 40 lb⌉ = 67
Quick reference
Storage and feeding waste are included. The share of body weight is a starting figure: body condition and your vet’s advice come first.
| Example | Bales to buy |
|---|---|
| 1,000 lb horse, 121 winter days | 67 |
| 1,000 lb horse for 30 days | 17 |
| 2 horses of 1,100 lb for a year | 443 |
| 1,200 lb horse, 60 lb bales, 182 days | 81 |
| Pony of 500 lb for 90 days | 25 |
| 1,000 lb at 1.5%, stored outside | 58 |
| 500 kg horse, 90 days, 20 kg bales | 50 |
| 3 horses of 450 kg for 180 days | 268 |
Where the numbers come from
The fixed figures this calculator relies on, and the published source each one was checked against. How the calculators are built and checked
3 sources
Crowl, E. Calculating Your Horse's Winter Hay Needs, University of Maryland Extension, updated April 7, 2021: "Horses should consume 2% of their body weight in hay. For example, a mature 1,000 pound horse should consume 20 pounds of hay per day." https://extension.umd.edu/resource/calculating-your-horses-winter-hay-needs
Used for
- Hay a horse eats in a day as a share of its body weight: 2%. A starting figure; body condition, work and a vet or nutritionist set the real amount.
Crowl, E. Calculating Your Horse's Winter Hay Needs, University of Maryland Extension, updated April 7, 2021: "We will assume 5% storage waste because our bales are stored inside"; "outdoor storage waste ranges from 5-35%". https://extension.umd.edu/resource/calculating-your-horses-winter-hay-needs
Used for
- Hay lost in storage when bales are kept inside: 5%. Outdoor storage loses 5 to 35%.
Crowl, E. Calculating Your Horse's Winter Hay Needs, University of Maryland Extension, updated April 7, 2021: "5% waste from feeding small square bales in a hayrack feeder"; "2,420 lbs x 1.05 (storage waste) x 1.05 (ground waste) = 2,668 lbs hay per horse". https://extension.umd.edu/resource/calculating-your-horses-winter-hay-needs
Used for
- Hay wasted at feeding when small square bales go in a hayrack feeder: 5%. Feeding on the ground wastes more.
Common questions about the Horse Hay Calculator
- How much hay does a horse eat a day?
- University of Maryland Extension starts from 2% of body weight a day, so 20 lb for a 1,000 lb horse. It is a starting point: an easy keeper, a hard keeper, a horse in work, a pregnant mare and a horse on pasture all differ. Body condition, and your vet's or an equine nutritionist's advice, decide the real amount.
- How many bales of hay does a horse need for winter?
- UMD's own example is a 1,000 lb horse fed 2% of body weight for 121 days, 1 December to 31 March: 2,420 lb eaten, 2,668 lb with 5% storage and 5% feeding waste, which is 67 bales of 40 lb. Heavier bales, a longer winter or more waste change it; the page works any of them out.
- Why add waste twice?
- Hay is lost in two places. Some spoils or is lost in storage, and some is trampled, soiled or dropped at feeding. UMD multiplies by 1.05 for each, which is what this page does. Its article notes that hay stored outside can lose 5% to 35%, and feeding on the ground wastes more than a hayrack.
- How many flakes should I feed?
- Flakes differ in weight from bale to bale and from field to field, so the page divides the hay fed a day by the weight of one flake of your bales: bale weight ÷ flakes in a bale. Weighing a few flakes is more accurate than counting them.
- Does this include grain or pasture?
- No. It assumes the whole share is fed as hay. If your horse gets pasture or concentrate, the hay it needs is less, and your vet or nutritionist can say by how much.