Calculators
Body Fat Calculator
Estimate body fat percentage with the US Navy circumference method from height, neck, waist and hip measurements.
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- Nothing uploaded
The tool
Enter your numbers below. Results update as you type, and nothing leaves your browser.
Everything you enter stays on your own machine. Nothing is sent to us or to anyone else, which you can confirm in your browser network tab.
What people use it for
- Tracking body composition changes
- Fitness assessments
- Comparing with BMI
- Setting fat-loss goals
About this tool
What the Body Fat Calculator does
The US Navy method estimates body fat from tape measurements and height using logarithmic formulas developed from body composition research. It needs only a tape measure and is more informative than BMI, though less precise than laboratory methods such as DEXA.
It also works as a body fat percentage calculator.
Formula
- Men: 495 ÷ (1.0324 − 0.19077 × log10(waist − neck) + 0.15456 × log10(height)) − 450
- Women: 495 ÷ (1.29579 − 0.35004 × log10(waist + hip − neck) + 0.221 × log10(height)) − 450
- Measurements in centimetres
Worked example
Using the starting values in the calculator above:
| Input | Value |
|---|---|
| Sex | Male |
| Height | 178 cm |
| Neck circumference | 38 cm |
| Waist circumference (at navel for men, narrowest for women) | 86 cm |
| Hip circumference (women) | 98 cm |
| Weight (optional) | 78 kg |
| Result | Value |
|---|---|
| Body fat | 17.2% |
| Category (ACE ranges) | Fitness |
| Fat mass | 13.4 |
| Lean mass | 64.6 |
How to read the result
Measure at the same time of day, relaxed, with the tape snug but not compressing the skin; take two readings and average them.
Track the trend rather than any single number; tape methods have an error of a few percentage points.
General information, not medical advice. Speak to a qualified health professional before making changes to diet, exercise or treatment.
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Questions
Questions about this tool
The things clients actually want to know — costs, timelines, ownership and what happens after launch.
Typically within a few percentage points of laboratory methods for most people.
Ranges differ by sex and age; the American Council on Exercise uses about 18–24% average for men and 25–31% for women.
At the navel for men and at the narrowest point for women in this method.
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