The RFM formula calculates your body fat percentage using only your height and waist measurement. The formulas for men and women are different.
RFM Formula
For men:
RFM = 64 - (20 × Height / Waist)
For women:
RFM = 76 - (20 × Height / Waist)
Or, using a single formula:
RFM = 64 - (20 × Height / Waist) + (12 × Sex)
Where Sex = 0 for men and Sex = 1 for women. Height and waist should be in the same units.
Example
Here's a calculation for a woman 165 cm tall, with a waist circumference of 75 cm.
RFM = 76 - (20 × 165 / 75) = 76 - (20 × 2.2) = 76 - 44 = 32%
An RFM of 32% is in the "Average" category for women.
RFM Categories
| Category | Men | Women |
|---|---|---|
| Essential Fat | < 10% | < 18% |
| Athletic | 10-20% | 18-28% |
| Fitness | 20-25% | 28-32% |
| Average | 25-30% | 32-40% |
| Obese | > 30% | > 40% |
History
RFM was first introduced in 2018 based on a dataset of over 12,000 adults. The purpose of RFM was to come up with a simple formula that could predict the body fat percentage without the need for expensive measurement devices.
When compared with DEXA scans (gold standard), RFM was able to accurately predict the body fat percentage in ~80% of cases. BMI could only predict in ~40% of cases.