Estimate your body fat percentage with the US Navy tape method — from height, neck and waist measurements.
How body fat is worked out
This body fat calculator uses the US Navy circumference method, which estimates body fat from simple tape measurements rather than special equipment. Enter your height and neck and waist measurements (plus hip for women).
It’s an estimate, not a precise clinical measurement, so treat it as a rough guide and track the trend over time.
How to fill it in
- Choose your sex.
- Measure and enter your height, neck and waist (and hip if female), in centimetres.
- Read your estimated body fat percentage and category.
The maths behind it
men: 495 ÷ (1.0324 − 0.19077·log₁₀(waist−neck) + 0.15456·log₁₀(height)) − 450
women use waist + hip − neck
A worked example
On the values this calculator opens with, the body fat is 16.4%. Underneath, Category comes out at Fitness and Fat mass est. at 16.4% of body weight. Change any field and every figure updates as you type.
Frequently asked questions
How accurate is the Navy body fat method?
It’s reasonably good for a tape-only method, usually within a few percent of more advanced measures, but it’s still an estimate.
How do I measure correctly?
Measure the neck below the larynx, the waist at the navel, and (for women) the hip at the widest point, keeping the tape level and snug.
What’s a healthy body fat percentage?
It varies by age and sex. Roughly, fitness ranges are about 14–17% for men and 21–24% for women. For guidance, consult a professional.