Enter your height and wrist circumference to estimate whether you have a small, medium, or large body frame.
How to Use the Body Type Calculator
Toggle to metric or US units, then choose female or male above the inputs — the ratio bands are sex-specific, so that choice matters as much as which unit system you're using. Fill in height and wrist size and the frame classification updates immediately.
Small, medium, and large frame here describes bone structure, not the twelve-type somatotype system (ectomorph, mesomorph, endomorph) that gets tossed around in fitness culture — that's a different, fuzzier idea entirely. This calculator measures something narrower: how much wrist a given height typically comes with, on the theory that wrist circumference tracks skeletal size better than almost anywhere else easy to measure. Wrist circumference is quick to check with a soft tape wrapped just below the wrist bone, which is part of why this method caught on outside clinical settings — no calipers, no scale, no second person needed.
Why Frame Size Gets Factored Into Weight Targets
Two people at the same height can carry meaningfully different amounts of bone and lean mass before either one is carrying any body fat at all — a large-framed person reasonably weighs more at a healthy composition than a small-framed person of identical height. That's the whole reason frame size shows up in some older "ideal weight" tables and body-composition assessments instead of relying on height alone: it's a crude correction for the fact that skeletons aren't all built to the same scale.
Ratio = Height (in) ÷ Wrist Circumference (in)For women, a ratio above 10.9 indicates a small frame, 9.9–10.9 a medium frame, and below 9.9 a large frame. Men run on a slightly lower scale — above 10.4 small, 9.6–10.4 medium, below 9.6 large — reflecting that men's wrists average larger relative to height than women's. A ratio sitting right at a boundary isn't a measurement error; it just means that body falls close to the dividing line the method draws, and either neighboring classification is a reasonable read.
Worth being upfront about where this comes from: it's a popularized fitness-industry heuristic built on general anthropometric conventions, not a single peer-reviewed clinical standard the way BMI's WHO bands are. Different trainers and old bodybuilding references have cited slightly different threshold numbers over the decades; this calculator uses one commonly repeated version of the method, not an official medical protocol.
An estimate, not a clinical measurement. Frame size from a wrist-to-height ratio is a rough classification, not a diagnosis of skeletal structure or a basis for medical decisions. For anything that actually matters for your health, talk to a doctor or a professional who can assess your body composition directly.