RFM Calculator
Estimate body fat percentage with Relative Fat Mass (RFM) using your height, waist, and sex.
Relative Fat Mass
Typical adult range.
RFM Category RangesMEN
RFM estimates body-fat percentage from height and waist circumference. Use this table to interpret your whole-number result by sex.
| RANGE | CATEGORY |
|---|---|
0-6% | Essential Extremely lean range that is hard to sustain for most people. |
6-14% | Athletic Lean, performance-focused range with strong definition. |
14-18% | Fitness Fit range often seen in regularly active men. |
18-25% | Average Common range in general adult populations. |
25+% | High Higher body-fat range. Prioritize sustainable habits and trend tracking. |
What Is Relative Fat Mass (RFM)?
Relative Fat Mass is a body-fat estimate based on height and waist circumference. Unlike methods that require neck, hip, or weight inputs, RFM is intentionally simple and relies on a waist-to-height relationship adjusted by sex.
The output here is shown as a whole-number percentage so it is easier to compare week-to-week. Use it as a trend tool, not a medical diagnosis.
RFM Formula Used
This calculator uses the classic equations:
Men
RFM = 64 - 20 x (height / waist)
Women
RFM = 76 - 20 x (height / waist)
Height and waist must be in the same units. The ratio makes the formula unit-consistent for inches or centimeters.
How To Measure Waist For Better Consistency
- Measure at the same point each time (usually around navel level).
- Keep the tape level and snug without compressing skin.
- Measure after a normal exhale and avoid stomach bracing.
- Take 2 to 3 readings and use the average.
How To Use This Result
RFM is best used to track direction over time. If measurements are consistent, the trend can show whether your body-fat level is moving up or down even if the exact percentage is imperfect.
For practical tracking, pair RFM with waist logs, progress photos, and performance markers. If you also want a height/weight-based lean-mass estimate, run the Lean Body Mass Calculator. For an anthropometric skeletal muscle estimate, compare with the Muscle Mass Calculator. For waist-height roundness context, use the BRI Calculator. For hip-adjusted waist context, use the Waist to Hip Ratio Calculator. For waist-height screening context, use the Waist to Height Ratio Calculator. For hip-height adiposity context, use the BAI Calculator. For caliper-based body-fat measurements, use the Skinfold Body Fat Calculator.
For deeper context, read Why Body Fat Calculators Are Inaccurate and Body Fat Calculator vs Body Fat Estimator.