Horse Feed Calculator

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Feeding rates as a percentage of body weight

The convention in equine nutrition is to express feed as a percentage of body weight, because that keeps the ration right whether the horse is a 500 lb pony or an 1,800 lb draft.

Work level	Forage (% of body weight)	Concentrate (% of body weight)	Total for a 1,000 lb horse
Maintenance / idle	2.0%	0%	20 lb hay
Light work	1.75%	0.25%	17.5 lb hay + 2.5 lb grain
Moderate work	1.5%	0.75%	15 lb hay + 7.5 lb grain
Heavy work	1.25%	1.25%	12.5 lb hay + 12.5 lb grain

As work increases, forage comes down and concentrate comes up — but long-stem forage should never fall below about 1% of body weight. Below that, the risk of gastric ulcers, wood-chewing and colic rises sharply.

Why you must weigh feed

A standard feed scoop holds anywhere from 1.5 lb to 5 lb of feed depending on the pellet or mix, and a "flake" of hay can weigh 2 lb or 8 lb. Estimating by volume is the single most common reason a ration is out by 30% or more.

Weigh hay once with a luggage or hanging scale and you will know your flakes for good. Then use the calculator above, switching the forage display to flakes or bales if that is how your hay is stored.

Adjust by body condition, not by the bag

The percentages above are a starting point for a horse in ideal condition (body condition score 5 of 9). The real control loop is: feed the ration, then re-score the horse every two to four weeks and move the ration up or down.

Two horses on the identical ration in identical work can end up 100 lb apart — a "hard keeper" and an "easy keeper" can differ by more than 30% in energy requirement. Score first: body condition score self-check.

Worked example

A 1,000 lb horse in light work:

Forage: 1,000 × 1.75% = 17.5 lb hay ≈ 4½ flakes at 4 lb each Concentrate: 1,000 × 0.25% = 2.5 lb grain Total: 20 lb of feed per day, split into at least two meals

Need the body weight first? Use the horse weight calculator.

Practical rules that matter more than the number

Change feed over 7–10 days. The hindgut microbiome needs time; abrupt changes cause colic and loose droppings.
Never exceed about 0.5% of body weight of concentrate in one meal. For a 1,000 lb horse that is 5 lb per meal, so 10 lb of grain means at least two feeds.
Free-choice clean water and loose salt at all times. A 1,000 lb horse drinks 5–10 gallons a day — see the water intake calculator.
Feed by weight, not by volume, and introduce a ration balancer if the hay is the only other source of vitamins and minerals.
Teeth and parasites first. A thin horse is more often a dental or parasite problem than a feed problem.

Frequently asked questions

How much hay should I feed my horse per day?

A common starting point is 1.5–2% of body weight in hay per day — 15–20 lb for a 1,000 lb horse — and never less than about 1% of body weight as long-stem forage.

How much grain does a horse need?

It depends on workload. An idle horse usually needs none. Light work takes about 0.25% of body weight, moderate work about 0.75% and heavy work about 1.25% — split across at least two meals.

Is 2% of body weight the right amount of feed?

About 2–2.5% of body weight per day in total feed suits most horses, including the hard-working ones. Use body condition score to fine-tune it rather than treating it as exact.

Can a horse live on hay alone?

Often yes, for an idle horse on good-quality hay — but hay alone is usually short on copper, zinc, selenium and vitamin E, so a ration balancer or vitamin-mineral supplement is worth adding.

Related tools and guides

Sources and method

Equine extension guidance on feeding 1.5–2.5% of body weight per day, with a minimum of roughly 1% as long-stem forage.
Ontario Ministry of Agriculture, Food and Rural Affairs — Estimating body weight for horses (for the weight figure rations are based on).

Page last reviewed 2026-10-16. Results are estimates from published formulas and are not veterinary advice.