Horse Weight Estimator
No livestock scale handy? The Carroll & Huntington tape formula estimates a horse's weight from two tape measurements — heart girth and body length. Enter them below for an instant estimate in pounds and kilograms, accurate enough for feed and dewormer math.
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How to use this calculator
With a soft measuring tape: run it around the barrel just behind the withers for heart girth, then measure body length in a straight line from the point of the shoulder to the point of the buttock. Enter both in inches.
Measure monthly and log the number — trends matter more than any single reading for feeding decisions.
How it works
Carroll & Huntington formula: weight (lb) = heart girth² × body length ÷ 330, with both measurements in inches. Example: 72² × 66 ÷ 330 ≈ 1,036 lb. Kilograms = pounds × 0.4536.
Tape estimates usually land within 30–50 lb of a scale — fine for feed and standard dewormer dosing, but use a scale for concentrated medications with narrow safety margins.
Frequently asked questions
What is the Carroll and Huntington formula?
Weight (lb) = heart girth² × body length ÷ 330, with both measurements in inches. It was developed from weighbridge data and remains the standard tape-based estimate.
How accurate is a weight tape estimate?
Usually within 30-50 lb for an average horse — good enough for feed and most dewormer dosing, but not a substitute for a scale when dosing concentrated medications.
Where do I measure heart girth and body length?
Girth: around the barrel just behind the withers and elbows. Length: from the point of the shoulder to the point of the buttock, in a straight line.
Why does my horse's weight matter?
Dewormers, sedatives, and many medications dose by weight — underdosing builds parasite resistance. Weight also tracks condition for feeding programs.
How often should I weigh my horse?
Monthly with a tape is plenty for most owners. Weigh before and after any feed change so you can see what the new ration actually does.