How Much to Feed a Horse: Hay, Grain, Water and Salt, Worked Out by Body Weight

By Gayle Woods Editors Updated 6 min read

Ask five horse owners how much they feed and you'll hear "two flakes morning and night," "a coffee can of sweet feed," and "whatever the last owner did." None of those tells you whether the horse is getting the right amount. Feeding a horse well comes down to a simple calculation that starts with its weight, and a few rules that keep its digestive system working.

Start with your horse's weight

Everything in a feeding plan is based on body weight, so get a real number.

  • A livestock scale is the most accurate. Some feed stores and vet clinics have one.
  • A weight tape wrapped around the girth, just behind the elbows and over the withers, gives a quick estimate, usually close enough for feeding.
  • The girth-and-length formula is more accurate than a tape for most horses: heart girth in inches, squared, times body length in inches, divided by 330. Body length runs from the point of the shoulder to the point of the buttock.

For example, a horse with a 72-inch girth and a 66-inch body length weighs about 72 × 72 × 66 ÷ 330 = 1,037 pounds. Our guide to measuring a horse shows where to place the tape.

Look at body condition as well. A horse can be the right weight for its frame and still carry too much or too little fat. Most vets use a 1-to-9 score, where 5 is ideal: you can feel the ribs easily but not see them.

Forage: the base of every diet

Horses evolved to graze for most of the day, and their gut needs a steady supply of fiber. Hay or pasture should make up most of what a horse eats.

  • Maintenance: about 2 percent of body weight in forage a day.
  • Minimum: about 1.5 percent of body weight. Less than that raises the risk of colic and ulcers.
  • Hard keepers, growing horses and horses in heavy work may eat 2.5 percent or more.
Horse weight 1.5% (minimum) 2% (typical) 2.5% (high)
800 lb (pony or small horse) 12 lb 16 lb 20 lb
1,000 lb 15 lb 20 lb 25 lb
1,100 lb 17 lb 22 lb 28 lb
1,300 lb 20 lb 26 lb 33 lb
1,700 lb (draft) 26 lb 34 lb 43 lb

Split the day's hay into as many meals as you can, or use a slow feeder or hay net so it lasts longer. A horse that finishes its hay in two hours and then stands with an empty stomach for ten is at higher risk of ulcers and colic.

Why you should weigh your hay

A flake is a slice of a bale, and its weight depends on how the bale was made and what's in it. Grass hay flakes often weigh 3 to 5 pounds. Alfalfa flakes are denser and can weigh 5 to 8 pounds. Two flakes might be 7 pounds or 15.

Weigh a few flakes from each new load with a hanging scale or a luggage scale, then convert your daily target into flakes. It takes five minutes, and you only need to repeat it when the hay changes.

Hay type matters too:

  • Grass hay such as timothy, orchard grass or brome is lower in calories and the standard choice for most adult horses.
  • Legume hay such as alfalfa is higher in protein, calcium and calories. It helps hard keepers and seniors but can make easy keepers fat.
  • Mixed hay falls between the two.

Good hay smells sweet, looks green, and has no mold, dust, weeds or dead animals in it. Feeding moldy hay can cause breathing problems and colic.

Pasture counts as forage

A horse on good pasture can eat 1.5 to 3 percent of its body weight in grass a day, and it may need little or no hay in the growing season. Keep two cautions in mind:

  • Lush spring grass is high in sugar. Overweight horses, ponies and horses with a history of laminitis may need a grazing muzzle or limited turnout. See our guide to laminitis.
  • Switch to pasture gradually. Start with 15 to 30 minutes a day in spring and add time over two to three weeks.

Grain and concentrates: only what hay can't cover

Many horses don't need grain at all. An adult horse in light work, on good hay, usually gets all the calories it needs from forage. What hay often lacks is vitamins and minerals.

  • Ration balancers are concentrated pellets fed at about 1 to 2 pounds a day. They add protein, vitamins and minerals without many calories. Most easy keepers should be on one, or a vitamin and mineral supplement, instead of grain.
  • Fortified feeds are meant to be fed at several pounds a day. Feed them at the rate on the bag, or the horse won't get the vitamins and minerals they're balanced for.
  • High-fat and high-fiber feeds add calories safely for hard keepers, seniors and horses in hard work.

The rules for feeding grain safely:

  • Keep each meal at or below about half a percent of body weight, or 5 to 6 pounds for an 1,100-pound horse. Large meals pass into the hindgut before they're digested and ferment there.
  • Feed hay before or with grain.
  • Weigh grain by the pound, not by the scoop. A scoop of pellets weighs very different amounts from a scoop of oats.
  • Change feeds slowly, over 7 to 10 days.

Water

A horse drinks about 5 to 15 gallons of water a day, or roughly a gallon per 100 pounds of body weight at rest. Heat, sweat, work, nursing and a dry hay diet can double that.

  • Keep clean water available all the time.
  • Scrub buckets and troughs often. Horses drink less from dirty water.
  • In winter, horses drink more when water is kept above freezing, ideally around 45°F to 65°F. An automatic waterer or trough heater helps prevent winter impaction colic.

Salt and electrolytes

Salt keeps horses drinking. An adult horse needs about 1 to 2 ounces of salt a day at rest, roughly 2 to 4 tablespoons, and more when it sweats.

  • Loose salt added to feed is the most reliable way to make sure a horse gets enough.
  • Salt blocks work for some horses, but many don't lick enough from a block, especially one made for cattle.
  • Electrolytes replace salts lost in heavy sweat. They help a horse working hard in the heat, not one standing in a field. See our electrolyte picks.

Two worked examples

A 1,100-pound Quarter Horse, easy keeper, trail ridden twice a week:

  • Hay: 22 pounds of grass hay a day, split into three or four feedings or fed from a slow feeder.
  • Ration balancer: 1 to 2 pounds a day.
  • Salt: 2 tablespoons of loose salt a day, more in summer.
  • Water: always available.
  • No grain.

A 1,200-pound Thoroughbred, hard keeper, in regular work:

  • Hay: 25 to 30 pounds of mixed grass and alfalfa hay, free choice if possible.
  • Concentrate: a high-fat, high-fiber performance feed at the label rate, split into two or three meals of no more than 5 pounds each.
  • Salt: 2 to 4 tablespoons of loose salt a day, plus electrolytes on hot, sweaty days.
  • Re-check body condition every two to four weeks and adjust. See how to put weight on a horse.

Sources

Frequently Asked Questions