What is RFM?

Relative Fat Mass (RFM) is a simple formula for the estimation of overweight or obesity in humans that requires only a calculation based on a ratio of height and waist measurements.

RFM formulas

For Men:
    RFM = 64 − (20 × height / waist)

For Women:
    RFM = 76 − (20 × height / waist)

Note: height and waist must be in the same unit (this calculator converts both to cm).
      

How to use

1. Select gender.
2. Enter your height and choose the unit.
3. Enter waist circumference and choose unit.
4. Click Calculate to see RFM % and category.

Example

Suppose Ali (male) has height = 175 cm and waist = 80 cm:

RFM = 64 − (20 × 175 / 80) = 64 − (20 × 2.1875) = 64 − 43.75 = 20.25%

Result: Ali's RFM = 20.25% → falls in Average range for men (18–24%).

Where to use this calculator?

Great for fitness sites, gym clients, health blogs, or personal trackers. Provide next steps like diet advice, exercise tips, or consultation prompts depending on category (optional).