Divide your height by your wrist circumference (both in cm). Women: over 11.0 = small, 10.1–11.0 = medium, under 10.1 = large. Men: over 10.4 = small, 9.6–10.4 = medium, under 9.6 = large. A smaller frame usually suits the lower end of the healthy BMI range, a larger frame the upper end.
Body Frame Size Calculator
How to measure your wrist
- Find your wrist bone (the bump on the little-finger side).
- Wrap a soft tape measure around the wrist just above the bone, towards your hand.
- Use your dominant hand and read the measurement in centimetres.
No tape? Try the finger test: wrap your thumb and middle finger around your wrist. If they overlap, you probably have a small frame; if they just touch, medium; if they do not meet, large.
Frame size chart
| Frame | Women (height ÷ wrist) | Men (height ÷ wrist) | Suggested part of healthy BMI range |
|---|---|---|---|
| Small | over 11.0 | over 10.4 | 18.5 – 22 |
| Medium | 10.1 – 11.0 | 9.6 – 10.4 | 20 – 24 |
| Large | under 10.1 | under 9.6 | 21.5 – 24.9 |
Frame size does not change the NHS healthy range (BMI 18.5–24.9). It just helps you choose a sensible target within it. See the ideal weight calculator.
Frequently asked questions
How do I know my frame size?
Measure your wrist just above the wrist bone and divide your height by it, or use the calculator above.
Does a large frame mean I can weigh more?
A large frame can put you towards the top of the healthy range, but not above it. A BMI of 25 or more is still classed as overweight.
Is frame size used by the NHS?
No. The NHS uses BMI and waist size. Frame size is an extra guide to help choose a target within the healthy range.
Related tools and guides
About this page
Sources
- NHS – Calculate your body mass index (BMI) for adults
- NICE NG246 – Overweight and obesity management (2025)
- Grant JP. Handbook of total parenteral nutrition (frame size by height-to-wrist ratio). 1980.
Medical disclaimer: this tool gives an estimate for adults and is not a diagnosis or medical advice. bmicalculatornhs.net is independent and not affiliated with the NHS. Speak to your GP, pharmacist or another qualified health professional about your own health. Full disclaimer.