Horse weight calculator

Measure the heart girth and the body length with a soft tape. You get the estimated weight in pounds and kilograms, using the formulas in the Merck Veterinary Manual.

Units

Heart girth (in)Body length (in)

Age

Heart girth. All the way round the body, just behind the shoulder and over the base of the withers, tape snug and level.
Body length. From the point of the shoulder to the point of the rump, with the horse standing square.

Estimated weight

1,108 lb

503 kg

Formula used: girth² × length ÷ 330
Maximum daily dry matter (2.5–3%): 28–33 lb

This formula reads slightly low, and tapes read lower still. Measure the same way each time and follow the trend.

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How it works

Heart girth is measured around the body just behind the shoulder, at the base of the withers. Body length is measured from the point of the shoulder to the point of the rump, with the horse standing square.

For an adult horse (over 2 years), weight in pounds = heart girth × heart girth × body length ÷ 330, in inches. For a yearling the divisor is 301 and for a weanling 280. In centimetres, the adult formula is girth² × length ÷ 11,880 for kilograms.

The Merck Veterinary Manual notes that the formula is closer to real weight than a weight tape but tends to slightly underestimate. Measure the same way each time and the trend is reliable even when the number is a little off.

Adult: lb = girth² × length ÷ 330 (inches). Yearling: ÷ 301. Weanling: ÷ 280.

Good to know

A scale is the only exact method. Use the estimate to follow changes and as a starting point.
Weight tapes do not suit miniature horses, donkeys or draft horses; treat any girth-based estimate for them with caution.
Ask your veterinarian before dosing a medicine from an estimated weight.

Frequently asked questions

How accurate is a horse weight tape?

Tapes are the least accurate tool and tend to underestimate. The girth-and-length formula is closer, but still slightly low; a scale is the only exact method.

Where do I measure heart girth?

All the way around the body just behind the shoulder, over the base of the withers, with the tape snug and level.

How much does a horse eat per day?

The Merck Veterinary Manual puts the maximum daily intake at about 2.5 to 3% of body weight in dry matter. Your veterinarian or nutritionist sets the actual ration.