HorseCalcs: Bootstrapped Figures for the Working Rider
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Horse weight calculator

No scale? Two tape measurements get you within about 3% of a horse's true weight. Choose your horse's age group, enter heart girth and body length in inches, and save the result to My Horse so the hay, feed and rider calculators fill it in for you.

Enter your numbers
Measurements
Age group
Around the barrel, just behind the elbow and over the withers
Point of shoulder to point of buttock

Estimated weight

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In kilograms
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Likely range (±3%)
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Weight-tape style estimate
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Measure the same way every time

Weigh-tape readings drift with how tight you pull and where you place the tape. Measure at the same spot, after the horse exhales, and track the trend over months rather than any single number.

How the tape method works

Adult weight (lb) = heart girth² × body length ÷ 330
Yearling: divide by 301  ·  Weanling: divide by 280

This is the Carroll and Huntington formula, developed by weighing horses on a scale and fitting their measurements. For average adult horses it lands within about 3% of true weight, which is far better than guessing and much better than a girth-only weight tape for long or short-bodied horses.

Taking the measurements

Heart girth: run a soft tape around the barrel just behind the front legs, over the highest point of the withers. Body length: from the point of the shoulder straight back to the point of the buttock. Keep the horse standing square on level ground.

When it's less accurate

The formula was built on average light horses. University of Minnesota research found it less reliable for drafts, ponies, miniatures and pregnant mares, so treat those results as a starting point. A livestock scale at your vet, feed store or fairgrounds is the only exact answer.

Once you know the weight, use it for the horse hay calculator and rider weight & horse size calculator.

Frequently asked questions

How accurate is the tape-measurement method compared to an actual scale?

It's commonly cited as accurate to within about 3% of true weight for most adult horses, which is precise enough for dosing dewormer or estimating feed — a certified livestock scale is more exact, but this method is a widely used, practical substitute when a scale isn't available.

Why does the formula change for yearlings and weanlings?

Young, growing horses have a different body proportion than mature adults — relatively longer legs and less filled-out frame — so using the adult divisor on a yearling or weanling would meaningfully overestimate their actual weight.

What is heart girth exactly, and where do I measure it?

It's the circumference of the horse's body measured just behind the front legs and withers, around the deepest part of the chest — getting the tape snug but not compressed, and level all the way around, matters more for accuracy than any other part of the measurement.

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