Horse weight calculator
No scale? Measure the heart girth and the body length with a soft tape and enter them here. The calculator applies the usual tape formula, girth² × length ÷ 330 with inches and pounds, or its metric version with centimetres and kilograms.
Runs in your browser: nothing you enter is sent anywhere.
How to use it
- Choose centimetres and kilograms or inches and pounds.
- Stand the horse square on level ground.
- Measure the heart girth and the body length and enter them.
- Read the estimated weight and the same in the other unit.
- Imperial: weight (lb) = girth² × length ÷ 330 (girth and length in inches)
- Metric: weight (kg) = girth² × length ÷ 11,880 (girth and length in cm)
Worked example
A horse with a 75 in heart girth and 65 in body length:
- 75² = 5,625;
- 5,625 × 65 = 365,625;
- 365,625 ÷ 330 = 1,108 lb, about 503 kg.
In centimetres: 190 cm girth and 165 cm length give 190² × 165 ÷ 11,880 = 501 kg.
Tips
- Measure at the same time of day, before feeding, to compare weeks fairly.
- Use the weight for feed rations and wormers, but ask your vet before dosing a medicine where exact weight matters.
- A body condition score alongside the weight shows whether the change is fat or growth.
Frequently asked questions
How do I measure heart girth and body length?
Heart girth goes around the barrel just behind the elbows and over the withers, where the girth of a saddle sits; read it as the horse breathes out. Body length goes from the point of the shoulder straight back to the point of the buttock. Use a soft tape, keep it snug but not tight, and measure twice.
What is the formula?
With inches: weight (lb) = heart girth² × body length ÷ 330. The metric version used in many countries is weight (kg) = heart girth² × body length ÷ 11,880 with centimetres. The two give results within about half a percent of each other.
How accurate is it?
For average riding horses tape formulas usually land within a few percent of a scale, but they are less reliable for very fit or very fat horses, heavily pregnant mares, drafts and minis. The main value is tracking change: measure the same way each time and watch the trend.
Does it work for foals and ponies?
Ponies, yes, within the same limits. Foals and young horses have different proportions, and the formula tends to be off for them; weigh them on a scale when you need an exact figure, for example for medication.
Can I use a weight tape instead?
A weight tape measures only heart girth and assumes an average body length. Adding the length, as here, accounts for long or short horses and is usually closer.