How to use the horse weight calculator
- Stand the horse square on firm, level ground.
- Measure the heart girth with a soft tape: around the barrel, just behind the elbows and over the withers. Read it as the horse breathes out.
- Measure the body length in a straight line from the point of the shoulder to the point of the buttock.
- Choose adult, yearling or weanling, and read the weight in pounds, kilograms and stone.
Switch to metric to enter centimetres. The calculator converts them, so the answer is the same formula either way.
The formula
Weight (lb) = heart girth² × body length ÷ 330, both in inches.
The divisor changes for young horses (Oregon State University Extension, “Weight Calculator”):
- Adult horse: 330
- Yearling: 301
- Weanling: 280
In metric, the same adult formula works out to about girth² × length ÷ 11,900 with centimetres and kilograms, close to the metric version (÷ 11,900) published by Carroll and Huntington (1988).
Tips
- Measure the same way each time. Same place, same time of day, same person. Then changes in weight are real, not measuring errors.
- Track it monthly. A falling weight can be the first sign of dental, worming or health problems.
- Use it for feeding. Feed and many care decisions are based on weight; ask your vet before giving any medicine by weight.
- Ponies and very heavy breeds differ in shape, so treat the result as a guide.
Sources
- Oregon State University Extension Service: Weight Calculator (horse: girth² × length ÷ 330; yearling 301; weanling 280).
- Carroll C.L. & Huntington P.J. (1988). Body condition scoring and weight estimation of horses. Equine Veterinary Journal 20: 41–45.
- University of Minnesota Extension: Hay in horse diets (about 2% of body weight a day).
Frequently asked questions
How do I estimate my horse's weight without a scale?
Use the tape formula: heart girth × heart girth × body length ÷ 330 = weight in pounds, with both measurements in inches (Oregon State University Extension). Use 301 instead of 330 for a yearling and 280 for a weanling. Measure as shown below the calculator.
How much does an average horse weigh?
It varies a lot by breed and build: ponies weigh far less than light riding horses, and heavy draught breeds far more. Measuring your own horse’s heart girth and body length with a weight tape is the only way to know.
How accurate is a horse weight tape?
A girth-only weight tape is a quick guide but can be well off for horses that are unusually long, short, fat or lean. The girth-and-length formula takes the body length into account, so it is usually a better estimate. A livestock scale is the only exact method.
How much does a horse weigh in kg?
Multiply pounds by 0.4536 to get kilograms; the calculator shows kilograms and stone automatically.
How much hay should a horse eat by weight?
University of Minnesota Extension says most horses should eat about 2% of their body weight in hay a day, and up to 2–2.5% when given free access. For a 1,000 lb (454 kg) horse, 2% is 20 lb (9 kg) of hay a day.