Horse Feed Calculator – How Much Hay Does My Horse Need?
Forage first. Enter your horse's weight and workload for a daily and weekly hay amount you can actually weigh out.
Your horse's daily forage
12.4 kg of hay a day
- Dry matter needed
- 10.5 kg a day
- Rate used
- 2.1% of body weight
- Hay per week
- 86.5 kg
- Roughly
- 4.3 small bales a week (at 20 kg)
Grazing counts towards this total – reduce hay when turnout increases.
Never drop below 1.5% of body weight in forage without advice from your vet or a qualified equine nutritionist.
Forage is the whole foundation
A horse's digestive system is built for near-continuous trickle feeding of fibre. The standard rule is that total forage – hay, haylage and grass combined – should provide two to two and a half per cent of body weight in dry matter each day. Horses in hard work sit at the top of that range; good doers and those needing to slim sit at the bottom. What you should not do is drop below about one and a half per cent without professional advice, because long gaps without fibre lead to gastric ulcers, colic and stress behaviours such as crib-biting.
Worked example: a 500 kg horse in light work
At two per cent, that is 10 kg of dry matter a day. Hay is around 85 per cent dry matter, so divide 10 by 0.85 and you need about 11.8 kg of hay as fed – roughly 82 kg a week, or four small bales. Split into three or four haynets so there is never more than a few hours without fibre, especially overnight.
Adjusting for work and weight
- Rest or light hacking: stay near two per cent.
- Moderate work: add around 0.2 percentage points.
- Hard work: up to 2.5 per cent, plus a hard feed or balancer as needed.
- Weight loss: reduce towards 1.5 per cent and increase work – never simply starve a horse.
- Weight gain: increase forage first, and add oil or a conditioning feed only if that is not enough.
Don't forget the grass
Grazing is forage, and horses are efficient at it – one to two kilograms of dry matter an hour is typical. A few hours on spring pasture can easily supply the entire daily ration, which is why hay in the stable on top of full turnout so often leads to weight gain and laminitis risk. Use strip grazing, a muzzle or restricted turnout rather than swapping grass for concentrates.
Weigh it, don't guess it
Hang a haynet on luggage scales. Sections of a bale vary enormously, and most yards discover they have been feeding a couple of kilos more or less than they thought. Weigh the hay dry before soaking, since soaking adds water but not dry matter. If you soak hay to reduce sugar, remember it loses some nutrients too, so a vitamin and mineral balancer is usually needed.
When to get professional help
Speak to your vet or a qualified equine nutritionist for horses with laminitis, PPID (Cushing's), equine metabolic syndrome, gastric ulcers or dental problems, and for youngstock, breeding stock and veterans. Those cases need a diet built around the condition rather than a general rule of thumb.
Frequently asked questions
How much hay should a horse eat a day?
Total forage should be about 2 to 2.5 per cent of body weight as dry matter. Since hay is roughly 85 per cent dry matter, a 500 kg horse on 2 per cent needs about 11.8 kg of hay as fed.
What does 'dry matter' mean?
It is the feed with the water removed. Hay is about 85 per cent dry matter, haylage nearer 65 per cent and fresh grass only around 20 per cent, so the same dry matter means very different weights on the scales.
Can I feed less than 1.5 per cent of body weight?
Not without veterinary or nutritionist supervision. Dropping below about 1.5 per cent of body weight in forage risks gastric ulcers, colic and stereotypies, and can be dangerous for a horse's gut.
How do I slow a greedy horse down?
Use small-holed haynets, double-net, split the ration into several nets around the stable or field, and use a trickle feeder. The goal is making the same amount last longer, not feeding less.
Should I weigh hay?
Yes. Use luggage scales on the haynet. A 'section' of a bale can vary from two to four kilograms, which is enough to make or break a diet.
Does grazing count?
Very much so. A horse at grass can eat one to two kilograms of dry matter an hour, so spring grass alone can exceed the whole forage allowance. Use a grazing muzzle, strip grazing or restricted turnout time.
When do I need hard feed?
Only when forage alone cannot meet energy needs, typically in hard work, for poor doers or for veteran horses. Most leisure horses need a balancer for vitamins and minerals rather than a bucket of hard feed.
Estimates only – not a substitute for advice from your vet.
Last reviewed: 22 September 2026