Body Frame Size Calculator

How This Calculator Works

Body frame size — small, medium, or large — is estimated here from the ratio between your height and your wrist circumference, a simple, widely-used method that only needs a tape measure around your wrist. Enter your gender at birth, height, and wrist circumference, and this calculator shows which frame size band you fall into and the exact ratio behind that result.

Frame size matters because it’s a genuine factor in how much a given body weight “looks like” on someone — two people at the same height and weight can have very different frames, since frame size reflects bone structure rather than fat or muscle. It’s sometimes used alongside a BMI or Ideal Weight result as extra context, since neither of those accounts for frame size on its own.

This is a much simpler method than clinical anthropometric approaches like the Heath-Carter somatotype system, which classifies body type (ectomorph/mesomorph/endomorph) from skinfold- caliper measurements taken by a trained professional — this calculator doesn’t attempt that, since it would need equipment and measurements this tool doesn’t collect.

The Formula

$$\vA{\text{Ratio}} = \frac{\vB{\text{Height}}}{\vC{\text{Wrist Circumference}}}$$

Both measurements use the same unit — the ratio itself is unitless, so it comes out identical whether you measure in centimeters or inches. The result is then compared against these commonly-cited bands:

A higher ratio means a wrist that’s small relative to height (a smaller frame); a lower ratio means a wrist that’s large relative to height (a bigger frame).

Worked Example

A male, height 70in (177.8cm), wrist circumference 7in (17.78cm):

1. $\vA{\text{Ratio}} = \vB{177.8} \div \vC{17.78} = 10.0$.
2. A ratio of 10.0 falls in the 9.6 to 10.4 range for men.

This corresponds to a Medium Frame.