Body Fat Calculator

Estimate your body fat percentage

This body fat calculator estimates body fat percentage using the US Navy circumference method. It needs only a tape measure, not special equipment. Along with body fat it shows a category, your fat mass, your lean mass and your BMI.

How to use it

1. Select male or female.
2. Choose Metric (cm and kg) or Imperial (inches and lbs).
3. Enter your height and weight.
4. Measure and enter your neck (just below the Adam's apple) and waist. Men measure the waist at the navel and women at the narrowest point.
5. Women also enter the hip measurement at the widest point.
6. Read your body fat %, category, fat mass, lean mass and BMI.

How it works

The US Navy method uses logarithms of your measurements. For men it uses waist − neck and height. For women it uses waist + hip − neck and height. Weight is not part of the body fat formula. It is used for the other results:

• Fat mass = weight × body fat % ÷ 100
• Lean mass = weight − fat mass
• BMI = weight in kg ÷ (height in m)²

Example: a person weighing 80 kg with 20% body fat has 80 × 0.20 = 16 kg of fat mass and 80 − 16 = 64 kg of lean mass. At 1.75 m tall, their BMI is 80 ÷ 3.0625 = 26.1 (Overweight band). Fat and lean mass are always shown in kg.

Body fat categories used

Category	Men	Women
Essential fat	2–5%	10–13%
Athletes	6–13%	14–20%
Fitness	14–17%	21–24%
Acceptable	18–24%	25–31%
Obese	25% and above	32% and above

BMI bands are under 18.5 underweight, 18.5–24.9 normal, 25–29.9 overweight and 30 or more obese.

Results are estimates for general information only and are not medical advice. Tape measurements are approximate, so speak to a health professional for an accurate assessment.

Frequently asked questions

How do I measure accurately?

Measure on bare skin, keep the tape level and snug without pressing in, and take each measurement two or three times.

Is body fat % better than BMI?

BMI uses only height and weight, so it cannot tell muscle from fat. A body fat estimate looks at body shape and can be more useful for tracking change over time.