Relative Fat Mass (RFM) Calculator
Get an estimate of your body fat percentage from just your height and waist measurements. A better formula than BMI — a measuring tape is all you need.
RFM formula: Men: 64 − (20 × height ÷ waist) | Women: 76 − (20 × height ÷ waist). Height and waist must both be in the same unit.
Stand straight and measure from head to foot.
Wrap the tape around your waist and breathe out.
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Estimated body fat (RFM)
This is an estimate, not medical advice. See a doctor for medical decisions.
RFM Categories (estimate)
| Category | Men | Women |
|---|---|---|
| Low | < 18% | < 25% |
| Healthy | 18–24% | 25–32% |
| Overweight | 25–29% | 33–38% |
| Obese | ≥ 30% | ≥ 39% |
How to use
- Select gender and unit.
- Enter your height and waist (at belly button level).
- Press "Calculate" to see your body fat % and category.
Frequently Asked Questions (FAQ)
What is the RFM calculator?
It estimates your body fat percentage from just your height and waist measurement using the Relative Fat Mass formula, which is a better guide than BMI — a measuring tape is all you need.
What measurements does the RFM calculator need?
Your gender, the unit system, and your height and waist measured at belly-button level, then press Calculate.
How do I read my result?
Compare your percent with the RFM category table on the page — Low, Healthy, Overweight or Obese — with separate ranges for men and women.
Is this a medical diagnosis?
No. RFM is an estimate from two measurements — useful guidance, not a medical diagnosis.