Horse Weight Calculator

Published horse weight equations

The calculator converts metric measurements to inches, applies the selected equation, and converts pounds to kilograms:

For example, a mature horse with a 70 in heart girth and 65 in body length gives (70² × 65) ÷ 330 = 965 lb, or about 438 kg. The output is rounded to whole kilograms and pounds because extra decimal places would imply precision that a tape estimate does not have.

The University of Minnesota publishes the separate 280 and 301 divisors for weanlings and yearlings. The mature 330 equation is documented by university equine and extension sources including the University of Tennessee, University of Connecticut, New Mexico State University and University of Arkansas.

Where to place the tape

Use a soft, non-stretch tape. Keep the horse standing square on level ground without a rug, saddle or other tack.

• Heart girth: pass the tape all the way around the barrel immediately behind the elbow and behind the highest point of the withers. Keep it snug and flat without indenting the body.
• Body length: measure from the point of the shoulder to the point of the buttock along the side. Do not measure from nose to tail.

A calm handler should control the horse. Stay beside the shoulder, never wrap the tape around your hand, and stop if the animal becomes unsettled. Repeat a reading if posture changes. For useful trend comparisons, measure with the same method and at a similar time of day; the University of Arkansas recommends morning before feeding.

What the result can and cannot tell you

This equation estimates current live body weight. It does not decide whether the animal is at a healthy or ideal weight, and it does not replace body-condition scoring. Pregnancy, obesity, very lean condition, illness, unusual conformation and measurement technique can change the relationship between girth, length and scale weight.

Do not use these equations for neonatal or unweaned foals, pregnant mares, donkeys, mules, recumbent animals or acutely ill animals. Draft and miniature horses may be better served by breed-type equations or a scale. University of Minnesota research provides more detailed four-measure breed-type equations using height and neck circumference; those are a different method and are not mixed into this simpler calculator.

Body weight matters for feeding, transport and veterinary care, but an estimate should not become an unsupervised dose calculator. UK veterinary product guidance recommends a scale or weight tape for dosing and directs owners to veterinary advice. Follow the veterinarian and the exact medicine label, especially for foals and drugs with narrow safety margins.

Sources: University of Minnesota young-horse feeding guidance, University of Minnesota adult bodyweight research, University of Tennessee Equine Welfare Series, University of Arkansas estimating guide, New Mexico State University equine guidance, and UK VMD authorised product guidance. Sources reviewed 16 July 2026.