RFM needs only a tape measure, making it a quick alternative to BMI for estimating body fat.
How to use the RFM Calculator
- Sex
- Height
- Waist circumference
Results update as you type, and every field accepts the units shown in its menu.
How it works
Divide height by waist circumference, apply the formula and add 12 for women.
Inputs explained
| Field | What to enter |
|---|---|
| Sex | Choose one: Male, Female |
| Height | Units: cm, m, mm, in, ft |
| Waist circumference | Units: cm, m, mm, in, ft |
Health note: this calculator is for education and screening only and is not a diagnosis or treatment advice. Discuss your results with a qualified clinician.
Formula
RFM = 64 − 20 × (height ÷ waist) + 12 × sex (sex = 1 for women, 0 for men)Worked example
Inputs — Sex: Male; Height: 175 cm; Waist circumference: 88 cm.
Results — Relative fat mass = 24.2 % body fat.
Frequently asked questions
Where should I measure the waist?
At the level of the belly button, standing.
How accurate is RFM?
Studies found it classified obesity more accurately than BMI, but it is still an estimate.
What formula does the RFM Calculator use?
RFM = 64 − 20 × (height ÷ waist) + 12 × sex (sex = 1 for women, 0 for men).