Horse Weight from Girth

About this calculator

Since few barns have a livestock scale big enough for a horse, weight is commonly estimated from tape measurements using a formula popularized by weight tapes: body weight (lb) = (heart girth in inches)² × body length (inches) ÷ 330, where heart girth is measured around the barrel just behind the front legs and withers, and body length runs from the point of the shoulder to the point of the buttock.

Horse owners and barn managers use this girth-and-length method for everyday tasks like dosing dewormer or medication accurately, since both are typically prescribed per kilogram or pound of body weight and overdosing or underdosing can be a real problem. It's also the standard way to track weight changes over time for a horse in training or recovering from illness, without needing a truck scale.

This calculator takes your horse's heart girth and body length measurements and returns an estimated body weight.