Body Fat Calculator
Estimate body fat percentage using the U.S. Navy circumference method.
The Formula
BF% = 86.01 × log₁₀(waist − neck) − 70.041 × log₁₀(height) + 36.76
U.S. Navy Method (women):
BF% = 163.205 × log₁₀(waist + hip − neck) − 97.684 × log₁₀(height) − 78.387
= 86.01 × log₁₀(85−38) − 70.041 × log₁₀(180) + 36.76
= 86.01 × 1.672 − 70.041 × 2.255 + 36.76
≈ 16.8% body fat
The U.S. Navy Body Fat Method
This calculator uses the U.S. Navy circumference method, which estimates body fat percentage from simple tape measure readings of your height, waist, neck, and (for women) hips. It is reasonably accurate — typically within 3–4 percentage points of laboratory methods like DEXA scanning — and requires no special equipment. The method was developed by the U.S. Navy for use in fitness assessments and remains one of the most practical field methods available.
How to Take Accurate Measurements
Precision matters. For the waist, measure at the narrowest point for women or at the navel for men. For the neck, measure just below the larynx (Adam's apple) for men, or at the narrowest point of the neck for women. For hips (women only), measure at the widest point. Take each measurement twice and average them. Stand relaxed — do not suck in. Inconsistent measuring technique is the biggest source of error with this method.
Healthy Body Fat Ranges
Body fat ranges vary by sex and fitness goal. For men: essential fat is 2–5%, athletes 6–13%, fitness 14–17%, acceptable 18–24%, obese 25% and above. For women: essential fat is 10–13%, athletes 14–20%, fitness 21–24%, acceptable 25–31%, obese 32% and above. Women naturally carry more essential fat due to hormonal and reproductive functions. Essential fat is the minimum needed for basic physiological function — going below it is associated with serious health consequences.
Frequently Asked Questions
What is a healthy body fat percentage?
For men, 10u201320% is generally considered healthy. For women, 18u201328% is healthy. Athletes typically fall in the lower ranges of these categories.