How is body fat calculated?

The US Navy formula estimates body fat from height, neck, waist (and hip for women).

It is indicative; a DEXA scan is the most accurate. Measure circumferences relaxed and snug.

Body Fat Calculator

Estimate your body fat percentage with the US Navy method from body measurements. See fat and lean mass. Free.

Height: 178 cm

Weight: 78 kg

Waist circumference: 85 cm

Neck circumference: 38 cm

16.4 %

Fitness

Fat mass	12.8 kg
Lean mass (muscle, bone, water)	65.2 kg

ℹ️ Uses the US Navy formula, which estimates body fat from body circumferences. The result is indicative — the most accurate measurement comes from a DEXA scan. Measure circumferences relaxed and snug to the skin.

The body fat calculator estimates how much of your body weight is fat, based on body circumference measurements. It offers a more detailed picture of body composition than BMI, with no special equipment required.

How the calculator works and what it’s for▾

How the estimate is formed

The calculator uses circumference measurements taken from different parts of the body and converts them into an estimated body fat percentage. The method relies on the fact that certain measurements correlate with the amount of body fat.

The result is a statistical estimate, so it does not replace precise measurement methods, but it gives a reasonable guideline at home.

What you enter and what you get

You enter the requested circumference measurements, and the calculator returns your estimated body fat percentage. You can compare the result against common reference ranges to understand your body composition.

Who it suits

This approach suits anyone training or simply wanting to track changes in body composition rather than the scale alone. Regular tracking reveals progress even when your weight stays the same.

Accuracy and tips

Always measure the same way, from the same spot and ideally at the same time of day, so the results stay comparable. A small measurement error affects the outcome, so repeat the measurement when needed.

🔄 Reviewed June 2026