Horse Hay Weight Calculator

Most healthy adult horses need roughly 1.5%-3% of their bodyweight in forage per day, with 2%-2.5% being the standard maintenance range recommended by the British Horse Society and World Horse Welfare. For a 500kg horse, that's roughly 7.5kg-15kg/day, with about 10-12.5kg/day being typical for maintenance. This calculator does that arithmetic for your horse's actual weight and your chosen rate.

Visual estimates are frequently wrong, sometimes by a large margin. The most reliable options are a proper equine weighbridge (many feed merchants, some livery yards and equine hospitals have one) or a weigh tape measured around the girth, used consistently in the same spot each time so you can also track changes over time. If you only have a rough estimate, it's still worth running the calculator — just treat the result as approximate too.

Hay is dried to a low moisture content (typically around 12%-15%), while haylage is wrapped at a higher moisture content (commonly 25%-45%), depending on how it was made. Because haylage contains more water per kilogram, you typically need to feed more of it by weight to supply the same amount of dry matter (the actual nutrition) that a given weight of hay would provide. This calculator doesn't change your entered percentage automatically for haylage — ask your nutritionist whether to increase it for your specific bale of haylage.

Because forage needs scale with a horse's bodyweight, not a flat number. A 300kg pony and a 700kg draft horse need very different daily amounts even at the same percentage. Using a percentage of bodyweight — the same method UK equine welfare bodies recommend — lets the calculator give you a genuinely personalised figure rather than a generic average.

For most healthy horses at a stable weight, 2%-2.5% of bodyweight/day (the calculator's default range) matches standard UK maintenance guidance. A lower rate around 1.5% is sometimes used for supervised weight-loss plans. A higher rate of 2.5%-3% may suit a horse a vet has confirmed is underweight, or a genuine hard keeper. Always start from what your current regime already looks like, and only change rate gradually.

The assessment compares your chosen feeding rate to the standard 1.5%-3% range from UK equine welfare guidance. Amber flags a rate at the low end (below 2%, appropriate only for a deliberate, supervised weight plan) or the high end (above 3%). Red flags a rate below 1.5%, which is below the usual welfare minimum for a horse's daily ration, or a very high custom rate. It's a guide to prompt a conversation with a vet or equine nutritionist, not a diagnosis.

Divide your weekly hay weight by your bale weight, then round up — you can't buy part of a bale. This calculator does that automatically for whichever bale size you select (small conventional, small, round, square, or a custom weight), and shows the result for both a week and a month.

No — it calculates forage need as if hay/haylage were the entire forage source. If your horse also gets significant turnout grazing, their actual hay/haylage requirement will usually be lower, particularly in spring and summer. Treat this calculator's figure as the amount needed for a stabled or largely forage-fed horse, and adjust down for grazing using your own judgement or a nutritionist's advice.

No. This tool only covers forage (hay/haylage) by weight. It doesn't calculate hard feed, balancers, or supplements — those depend on workload, condition and specific product feeding rates that a feed manufacturer or nutritionist is better placed to advise on.

Not reliably. Percentage-of-bodyweight forage guidance is aimed at mature horses and ponies. Foals, weanlings and yearlings have different, growth-related nutritional needs and should be fed under guidance from a vet or equine nutritionist rather than an adult maintenance percentage.

The monthly figure is calculated as daily total × 30 as a simple, stated approximation. Real months are 28-31 days, so your actual monthly hay use will vary by a day or two's worth of forage either way — for ordering purposes, round up rather than down.

No. Any change to a horse's diet, including hay amount or a change of hay source or batch, should happen gradually over a minimum of 10-14 days. Horses have a documented higher colic risk in the two weeks after a sudden dietary change, because the hindgut bacteria that digest forage need time to adjust. See the timeline section above for a practical transition approach.

Run the calculator once per horse, or once per group of horses that are a similar size and get the same rate, and add the totals together. Entering an average bodyweight across very different horses will overstate the requirement for your smaller horses and understate it for your larger ones.

No. It gives an estimate only, based on published UK equine welfare guidance (British Horse Society and World Horse Welfare). It does not assess your horse's individual body condition, health, workload or any medical conditions. Always speak to a vet or a registered equine nutritionist for advice tailored to your horse, particularly if your horse needs to gain or lose weight, or has a health condition such as laminitis, EMS or PPID.

The British Horse Society's feeding-horses guidance and World Horse Welfare's feeding advice are both freely available online and are the two sources this calculator's percentage range is drawn from — see the Sources section below for direct links.