Body Fat Percentage Calculator
Formula
BF% = 1.2×BMI + 0.23×Age − 10.8×Sex − 5.4
The Deurenberg formula estimates body fat from BMI, age, and sex. Male: sex=1, Female: sex=0. This is an estimate — for accurate measurement, use calipers or DEXA scan.
How to use
- Enter your BMI value.
- Enter your Age in years.
- Choose your Sex, then read the estimated Body Fat %.
Example
A 30-year-old male with a BMI of 24 has an estimated body fat of 19.5% (1.2×24 + 0.23×30 − 10.8×1 − 5.4), within the healthy range for men.
Frequently Asked Questions
What is a healthy body fat percentage?
Men: 10-20% (athletes 6-13%). Women: 18-28% (athletes 14-20%).
Is this accurate?
It's an estimate based on BMI. Direct measurement methods (DEXA, calipers) are more accurate.
Why does this formula need my age and sex?
The Deurenberg formula uses age because body fat tends to rise over the years even when BMI stays the same, as muscle is gradually replaced by fat. Sex is included because women carry more essential fat than men at any given BMI, so the formula subtracts a larger amount for males. Feeding in both factors makes the estimate more realistic than BMI alone, which ignores them entirely.
What is essential body fat?
Essential body fat is the minimum amount your body needs to function, supporting organ protection, hormone production, and temperature regulation. It's roughly 2 to 5 percent for men and 10 to 13 percent for women, with the higher level in women linked to reproductive health. Dropping below these floors is dangerous, which is why even competitive athletes rarely sustain single-digit body fat for long.