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Body Fat Calculator
Estimate body fat percentage with the US Navy tape-measure method, plus fat mass, lean mass and your ACE category.
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How to use this calculator
Enter your values after choosing the type of calculation in the tabs. The result updates as you type; press Calculate to confirm and jump to the result on mobile. Use Share to send the calculator with your result.
The US Navy formula
The Navy method uses circumferences and height (all in inches) instead of skinfold calipers. It was developed at the Naval Health Research Center (Hodgdon & Beckett, 1984) and is still used for military body-composition screening.
Men: %BF = 86.010 × log₁₀(waist − neck) − 70.041 × log₁₀(height) + 36.76
Women: %BF = 163.205 × log₁₀(waist + hip − neck) − 97.684 × log₁₀(height) − 78.387
Example: a man 70 in tall with a 34 in waist and 15 in neck: 86.010 × log₁₀(19) − 70.041 × log₁₀(70) + 36.76 ≈ 17.5%, at the top of the ACE “Fitness” range.
Body fat categories
| Category | Women | Men |
|---|---|---|
| Essential fat | 10–13% | 2–5% |
| Athletes | 14–20% | 6–13% |
| Fitness | 21–24% | 14–17% |
| Average | 25–31% | 18–24% |
| Obese | 32% + | 25% + |
Source: American Council on Exercise (ACE) body-fat categories, as published in the ACE Body Composition chart. These are general ranges for adults, not health targets.
How to measure
- Waist: horizontally at the navel for men; at the narrowest point for women. Relaxed, don’t suck in.
- Neck: just below the larynx (Adam’s apple), tape sloping slightly down to the front.
- Hips (women): around the widest part of the buttocks.
- Measure on bare skin, snug but not compressing, and average two or three readings.
Accuracy and limits
Every field method has error. DEXA, hydrostatic weighing and air displacement (Bod Pod) are more accurate, but cost more. The Navy method tends to be least accurate for very lean, very muscular or very large people. Track the trend with the same method rather than chasing one number.
Frequently asked questions
What is a healthy body fat percentage?
ACE lists 14–24% (fitness to average) for adult men and 21–31% for adult women. Essential fat is about 2–5% for men and 10–13% for women.
How accurate is the Navy body fat method?
For most adults it lands within roughly 3–4 percentage points of laboratory methods, but it can be off more for very lean or very muscular people.
Why do women have a higher healthy body fat range?
Women carry more essential fat, linked to reproductive and hormonal function.
About this tool
- Written by
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- Expert review pending
- Last updated
- 31 Oct 2026
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