Calculadora de Gordura Relativa (RFM)
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
Formula
RFM = 64 − 20·(altura/cintura) [+ 12 para mulheres]
About this calculator
The Relative Fat Mass (RFM) calculator estimates body fat percentage non-invasively using only height and waist circumference. Developed by researchers at Cedars-Sinai Medical Center, RFM is an alternative to BMI and skinfold measurements. The base formula is 64 - 20 × (height / waist), with an additional 12 points for women, as they naturally have more fat. The result is a percentage indicating the proportion of fat in the body.
To use the calculator, measure your height in meters and waist circumference at the navel level, in meters. Divide height by waist, multiply by 20, and subtract from 64. If you are a woman, add 12. For example, a man 1.80 m tall with a waist of 0.90 m: 64 - 20 × (1.80 / 0.90) = 64 - 20 × 2 = 64 - 40 = 24% body fat. RFM is useful for assessing health risks associated with excess abdominal fat.
When to use? RFM is indicated for adults aged 18 to 80, in clinical, academic, or self-care settings. It helps monitor body composition changes during diets or workouts. Caveats: accuracy may be lower in very muscular athletes or people with morbid obesity. The waist should be measured without skin compression. It does not replace full medical evaluations but serves as a simple screening tool.
Frequently asked questions
What does RFM mean?
RFM stands for Relative Fat Mass. It is a method to estimate body fat percentage using height and waist circumference.
Is RFM more accurate than BMI?
RFM is often more accurate than BMI for estimating body fat because it accounts for abdominal fat distribution. However, no method is 100% accurate.
How to measure waist correctly for RFM?
Measure waist circumference at the navel level, with the tape horizontal and snug but not compressing the skin. Take the measurement at the end of a normal exhale.
Does RFM work for children and elderly?
RFM was validated for adults aged 18 to 80. For children and those over 80, accuracy may be lower. Consult a healthcare professional.
What is a healthy RFM range?
For men, healthy is 10-20%; for women, 20-30%. Higher values indicate excess fat. See your doctor for personalized interpretation.