Only a tape measure
The US Navy method estimates body fat from circumferences, so you need no scales or clinic — just a measuring tape.
CalculatorsRuns in your browser
Body Fat Calculator (US Navy Method)
Body-fat percentage from a tape measure, plus lean and fat mass.
- Input
- No upload needed — instant
- Privacy
- Nothing is uploaded
- Cost
- Free · no sign-up · no watermark
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Overview
About the Body Fat Calculator (US Navy Method)
Estimate your body-fat percentage with the US Navy circumference method from height, neck, waist and hip, and see your fat mass, lean mass and fitness category.
Body-fat percentage tells you more than weight alone, because it separates fat from muscle. This calculator uses the US Navy circumference method — height, neck, waist and hip — to estimate it with nothing but a tape measure, then converts it into fat mass and lean mass.
The formula
Men: BF% = 495 ÷ (1.0324 − 0.19077·log10(waist − neck) + 0.15456·log10(height)) − 450
Women: BF% = 495 ÷ (1.29579 − 0.35004·log10(waist + hip − neck) + 0.22100·log10(height)) − 450All measurements are in centimetres; imperial inputs are converted for you.
Reading the result
The ACE categories give the number context — athlete, fitness, average or high — with different ranges for men and women. Pair body fat with your weight to see lean mass, which is the figure to protect when you lose weight.
Private and precise
This calculator produces estimates from published formulas and is not medical advice. For anything about your health, talk to a doctor or a registered dietitian.
Step by step
How to use the Body Fat Calculator (US Navy Method)
Choose units and your biological sex.
Measure your height, neck, waist (and hip if you are a woman) with a tape.
Read your body-fat percentage, fat mass, lean mass and category.
Why use it
Benefits and common use cases
What this tool is good for, and what it deliberately does not try to do.
Lean and fat mass
Combines the percentage with your weight to show how many kilograms or pounds are fat and how many are lean.
Category context
Compares your result against the American Council on Exercise ranges for men and women so the number means something.
Questions
Frequently asked questions
Short, honest answers about quality, limits and privacy.
How accurate is the US Navy method?
It is a useful, consistent estimate that needs only a tape measure, but it can be off by a few percentage points versus lab methods like DEXA or hydrostatic weighing. Track the trend over time rather than trusting a single reading.
Where do I measure?
Men: waist at the navel and neck just below the larynx. Women: waist at the narrowest point, hip at the widest, and neck below the larynx. Keep the tape snug but not compressing the skin.
What is a healthy body-fat percentage?
By ACE ranges, men are typically 6–24% and women 14–31%, with athletes at the lower end. Essential fat is about 2–5% for men and 10–13% for women and cannot go below safely.