Body Fat Calculator
Estimate your body fat percentage using the US Navy circumference method.
Reviewed October 7, 2026 Runs in your browser — inputs are never stored
This tool provides general educational estimates only and is not medical advice. It does not diagnose, treat, or replace guidance from a qualified healthcare provider. Consult a doctor for decisions about your health.
About the Body Fat Calculator
The body fat calculator estimates your body fat percentage with the U.S. Navy circumference method. It uses your height and neck and waist measurements (plus hips for women) and needs nothing more than a tape measure. Body fat percentage is a better guide to body composition than weight or BMI because it separates fat from muscle, bone and water. The Navy formula is typically within about 3–4 percentage points of laboratory methods such as DEXA, so it is best used to track changes over time with consistent measurements rather than as an exact figure.
How to use it
- 1Choose metric or imperial units and select your sex.
- 2Measure your height without shoes.
- 3Measure your neck just below the larynx and your waist at the navel (men) or at the narrowest point (women).
- 4Women also measure the hips at the widest point.
- 5Press Calculate to see your estimated body fat percentage and category.
Worked example
a man 175 cm tall with a 38 cm neck and an 85 cm waist has an estimated body fat of about 16.9%, which falls in the “Fitness” range for men. A woman 165 cm tall with a 34 cm neck, 76 cm waist and 100 cm hips comes out at about 29.4%.
How it works
How it works
The US Navy formula uses your height and the circumference of your neck, waist (and hips for women) to estimate body fat percentage.
Who it is for
People tracking a fat-loss or muscle-building programme and anyone who wants a more informative measure than the bathroom scale.
Why it helps
Fat and muscle weigh the same on a scale; body fat percentage shows which one is changing.
Common use cases
- Tracking progress during a fat-loss phase
- Checking that weight gained while training is mostly muscle
- Comparing your result with typical ranges for your sex
Common mistakes to avoid
- Measuring after a meal or a workout, when the waist and neck can read differently.
- Pulling the tape tight enough to compress the skin.
- Comparing a Navy-method result directly with a smart-scale reading; the methods differ.
Frequently asked questions
A:It is a reasonable estimate for most people but less precise than methods like DEXA scans.
A:Measure snugly but without compressing the skin, keeping the tape level around the body.
Reviewed for accuracy · Last updated October 7, 2026
Formulas follow recognised clinical references — including WHO BMI classifications, the Mifflin-St Jeor equation, and Naegele’s rule — and are periodically checked against published reference values.
CalcWisee Editorial Team
Calculator development and formula review
CalcWisee is an independent site founded by Ayman. Every calculator is built from a published formula or official definition, tested against hand-worked examples before it goes live, and corrected promptly when a reader reports an issue to ayman@calcwisee.com.
Expertise: Financial mathematics, Health and fitness formulas, Applied mathematics, Unit conversion standards
References & sources
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