How is frame size determined?

It divides your height by your wrist circumference to get a ratio (r). For women, r above 11 is a small frame, 10.1 to 11 is medium, and below 10.1 is large. For men the thresholds are 10.4 and 9.6.

Why does frame size matter?

Frame size helps interpret ideal-weight ranges and BMI. Two people of the same height can have healthy weights that differ because one has a larger bone structure.

Where do I measure my wrist?

Wrap a tape measure around the wrist of your dominant hand just below the wrist bone, toward the hand, where the wrist naturally bends.

Does it matter if I measure in inches or centimetres?

No, as long as height and wrist use the same unit. The ratio is unit-consistent — the tool converts both measurements to a common unit before dividing, so the same body gives the same ratio either way.

Is frame size the same as BMI?

No. BMI is based on weight and height only and does not account for bone structure. Frame size is a separate measure that helps you interpret where in a healthy-weight range you might sit, since a large-framed person can weigh more at the same height while still being healthy.

Body Frame Size Calculator

Body frame size calculator

Your body frame size — small, medium or large — describes your underlying bone structure, and it helps put ideal-weight ranges and BMI into context: two people of the same height can both be healthy at quite different weights. This calculator estimates your frame from your height and wrist circumference using the widely used height-to-wrist ratio method, with separate thresholds for men and women.

How it works

The tool divides your height by your wrist circumference (after converting both to the same unit) to get a ratio r, then compares it to sex-specific cut-offs. A larger wrist relative to height gives a smaller ratio and a larger frame:

Sex	Small frame	Medium frame	Large frame
Women	r > 11	10.1 – 11	r < 10.1
Men	r > 10.4	9.6 – 10.4	r < 9.6

Measure your wrist just below the wrist bone, where it bends, on your dominant hand.

Example

A woman who is 165 cm tall with a 15 cm wrist circumference has a ratio of 165 ÷ 15 = 11.0. That falls in the 10.1–11 band, so her result is a medium frame. If her wrist measured 14 cm, the ratio would be 165 ÷ 14 ≈ 11.8 — above 11 — giving a small frame.

Results are estimates for general guidance, not medical advice, and are calculated privately in your browser — nothing is uploaded.