How to measure correctly
- Neck: just below the larynx, tape sloping slightly down at the front.
- Waist: at the navel for men; at the narrowest point for women.
- Hip (women): around the widest point of the hips.
- Keep the tape snug but not compressing the skin, and measure after breathing out normally.
About the US Navy method
This calculator uses the US Navy circumference formula, which estimates body fat from height and a few tape measurements. It's free, needs no equipment, and is reasonably accurate for most people — typically within about 3–4% of a proper body-composition scan. It's less reliable for very muscular or very lean individuals. Treat it as a useful trend tracker (measure the same way each time) rather than a precise clinical figure, and consult a professional for health decisions.
Benefits
- Estimates body fat with the US Navy tape method — no equipment needed.
- Metric and imperial units, with correct male and female formulas.
- Also estimates fat mass and lean mass when you enter your weight.
- Shows which category your result falls into.
Limitations to know
- Circumference formulas are estimates, typically within about 3–4% of a DEXA scan.
- Less accurate for very muscular or very lean people.
- It is general information, not medical advice.
Common mistakes to avoid
- Measuring in a different place or tension each time, which ruins comparability.
- Pulling the tape tight enough to compress the skin.
- Treating one reading as exact instead of tracking the trend.
Alternatives
For a simpler height/weight measure use the BMI Calculator; for calorie needs use the BMR & TDEE Calculator.
Last updated: August 2026 · Reviewed by the AI Toolbox editorial team.
Frequently asked questions
How accurate is it?
Usually within about 3–4% of a DEXA scan for average builds. It's most useful for tracking change over time.
Why do women need a hip measurement?
The Navy formula uses different equations by sex; the female version includes hip circumference for better accuracy.
What's a healthy body fat percentage?
See the category table — it differs for men and women. Essential fat is higher for women for physiological reasons.
Is my data stored?
No — everything is calculated in your browser.