Horse weight calculator
Fill in the fields above and press Calculate.
top — code ready, activates once AdSense is approvedHow to measure your horse
Two measurements are all you need. Both are taken with the horse standing square on level ground.
- Heart girth — run a soft tape all the way around the barrel, just behind the elbow and over the lowest point of the withers. Pull it snug against the coat, not tight, and read the number at the end of a normal exhale.
- Body length — measure the straight-line distance from the point of the shoulder (the bony bump at the front of the chest) to the point of the buttock. Do not follow the curve of the body; a curved measurement overstates length and inflates the result.
If you are measuring in centimetres, switch the units selector above — the calculator applies the metric form of the formula automatically. A dedicated walkthrough with the common mistakes is in how to use a weight tape.
How the weight-tape formula works
The tape formula treats the horse’s barrel as a rough cylinder. Girth gives the circumference, so it is squared to approximate cross-sectional area; multiplying by body length approximates volume; dividing by a constant converts that volume into weight for a horse of average density.
The divisor changes with the animal because density and body shape differ:
| Animal | Divisor (inches) | Why |
|---|---|---|
| Adult horse | 330 | Standard light-breed adult |
| Pony | 299 | Ponies are denser and shorter-barrelled for their girth |
| Yearling | 301 | Still growing, different body proportions |
| Weanling / foal over 2 months | 280 | Immature proportion of bone, muscle and gut |
Foals under about two months old are measured differently, because growth is so rapid that the girth-and-length model breaks down. Tick the foal box above and the calculator switches to the young-foal formula:
inArticle — code ready, activates once AdSense is approvedA worked example
An adult horse with a heart girth of 72 inches and a body length of 68 inches:
In metric, a girth of 183 cm and a length of 173 cm gives 183² × 173 ÷ 11,900 = 487 kg ≈ 1,073 lb. The two formulations agree to within about 0.2%, which is why either unit works.
What to do with the number
Weight is the input to almost every other decision in horse care, and it is why this site exists:
- Work out a rationHay and concentrate as a percentage of this body weight.
- Plan winter hayHow many bales a horse, or a herd, will get through.
- Dose a dewormerDose volume is calculated from body weight — getting it wrong causes resistance.
- Check water intakeNormal intake scales with body weight, weather and work.
- Score body conditionWeight alone cannot tell you whether the horse is fat or thin.
- Compare with the normExpected weight band for your horse’s height and build.
How accurate is a weight tape?
For an average light-breed horse in moderate condition, the tape formula lands within roughly 3–5% of a true scale reading. A 1,000 lb horse therefore carries an uncertainty of about 30–50 lb.
Accuracy falls away for draft breeds, ponies, foals, very fat or very thin horses, heavily pregnant mares and heavily muscled horses. For routine feeding that is plenty. For weight-critical medication it is not — use a livestock scale if one is available, and read how accurate the weight tape really is in detail.
Nothing here replaces veterinary advice. These calculators reproduce published estimation formulas. Dosages, diets and condition decisions for an individual horse belong with your vet or an equine nutritionist.
Frequently asked questions
How do I calculate my horse’s weight without a scale?
Measure the heart girth in inches, measure the body length in inches, then calculate girth squared multiplied by length, divided by 330 for an adult horse. A 72-inch girth and 68-inch length gives 72 × 72 × 68 ÷ 330 = about 1,068 lb.
Is the weight tape formula accurate?
Within roughly 3–5% of a scale for average light-breed horses in moderate body condition. It is least reliable for draft horses, ponies, foals, and horses that are very fat or very thin.
Why is the divisor different for ponies and foals?
Because the formula converts a volume into a weight, and it assumes average body density. Ponies are denser and shorter-barrelled than horses for the same girth, while foals have a much smaller share of their body as gut and muscle, so each group needs its own constant.
Should the measurement be in inches or centimetres?
Either — the calculator switches formulas for you. Never mix the two: a girth in centimetres with a length in inches will produce a wildly wrong answer.
Where exactly is the heart girth measured?
Around the barrel, just behind the front legs at the elbow, and across the lowest point of the withers. Take the reading at the end of a normal exhale with the horse standing square.
footer — code ready, activates once AdSense is approvedRelated tools and guides
- How to Use a Horse Weight TapeA practical walkthrough for measuring a horse with a weight tape: where to place the tape, how to read it at t…
- How Accurate Is a Horse Weight Tape?Weight tapes land within a few percent on average horses but miss badly on drafts, ponies, foals and very fat …
- Horse Weight ChartReference tables of typical horse weights by height and build, by breed and type, and at birth and weaning. Us…
- Ideal Weight for Horse HeightFind the expected weight range for a horse of a given height and build, and compare it with the actual weight.…
- Horse Feed CalculatorWork out how much to feed your horse each day. Enter body weight and work level to get daily hay and concentra…
Sources and method
- Ontario Ministry of Agriculture, Food and Rural Affairs — Estimating body weight for horses.
- NSW Department of Primary Industries — Primefact 928: Estimating a horse’s condition and weight.
- Carroll, C.L. & Huntington, P.J. (1988) — the girth-and-length body weight formula used on weight tapes.
Page last reviewed 2026-10-16. Results are estimates from published formulas and are not veterinary advice.