Free Body Fat Calculator (US Navy Method) with Categories
Estimate body fat percentage from height, neck, waist (and hip for women) with the US Navy circumference method. No calipers needed.
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About this calculator
Body fat percentage is a more useful health marker than weight alone because it separates fat from muscle, bone and water. The US Navy circumference method estimates it from a tape measure, which makes it easy to repeat at home.
Measure in the morning, relaxed and unclothed. Take each measurement twice and use the average.
How it works
For measurements in centimetres:
Men: % fat = 495 ÷ (1.0324 − 0.19077 × log10(waist − neck) + 0.15456 × log10(height)) − 450
Women: % fat = 495 ÷ (1.29579 − 0.35004 × log10(waist + hip − neck) + 0.22100 × log10(height)) − 450
Where to measure: neck just below the larynx; waist at the navel for men (and the narrowest point for women); hips at the widest point.
How to read your result
| Category | Men | Women |
|---|---|---|
| Essential fat | 2–5% | 10–13% |
| Athletes | 6–13% | 14–20% |
| Fitness | 14–17% | 21–24% |
| Average | 18–24% | 25–31% |
| Obese range | 25%+ | 32%+ |
Categories are those published by the American Council on Exercise. Track the trend over weeks, not day-to-day changes.
Worked example
A man, 178 cm, neck 38 cm, waist 90 cm, weighing 80 kg.
| Body fat | 20.1 % Average |
| Fat mass | 16.1 kg |
| Lean mass | 63.9 kg Muscle, bone, organs and water |
Frequently asked questions
How accurate is the Navy body fat method?
It typically lands within about 3–4 percentage points of DEXA scans for most people but can be less accurate for very lean, very muscular or very obese individuals.
What is a healthy body fat percentage?
Roughly 14–24% for men and 21–31% for women covers fitness to average ranges. Healthy ranges vary with age.
Why do women need a hip measurement?
Women store more fat around hips, and the formula includes hip circumference to reflect this.
Is body fat better than BMI?
They answer different questions. BMI is a screening tool based on weight and height. Body fat directly estimates composition.
Limitations and when not to use
Estimates only; not valid for children, pregnancy or people with significant fluid retention. For clinical assessment use DEXA, BIA or skinfold measurements by a professional.
Sources and references
- Hodgdon JA, Beckett MB. Prediction of percent body fat for U.S. Navy men and women from body circumferences and height. Naval Health Research Center Report 84-29, 1984.
- American Council on Exercise. Percentage of body fat categorization.
Last updated: 2026-10-09