Body Fat Percentage Calculator
This body fat calculator uses the U.S. Navy circumference (tape) method to estimate your body fat percentage from a few simple measurements — no calipers or scale required. Add your weight to also see fat mass and lean mass.
How the Navy method works
The U.S. Navy (Hodgdon–Beckett) method estimates body fat from body circumferences and height rather than skinfolds. Measuring in centimetres, the formulas are:
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)) − 450
How to take each measurement
- Neck: around the neck just below the larynx (Adam's apple), tape sloping slightly down at the front.
- Waist (men): horizontally at the navel, relaxed — don't suck in.
- Waist (women): at the narrowest part of the torso.
- Hip (women): around the widest part of the hips/buttocks.
Keep the tape snug but not compressing the skin, and take each measurement two or three times to average out error.
Worked example
A man 178 cm tall with a 40 cm neck and 90 cm waist: %BF = 495 ÷ (1.0324 − 0.19077·log₁₀(50) + 0.15456·log₁₀(178)) − 450 ≈ 18.7%, which falls in the "Average" range on the table below.
Body fat percentage categories
| Category | Men | Women |
|---|---|---|
| Essential | 2–5% | 10–13% |
| Athletes | 6–13% | 14–20% |
| Fitness | 14–17% | 21–24% |
| Average | 18–24% | 25–31% |
| Obese | 25%+ | 32%+ |
Source: American Council on Exercise (ACE) body-fat categories.
Accuracy & alternatives
The tape method typically lands within ±3–4% of a DEXA or hydrostatic measurement — accurate enough to track change over time, but not a clinical reading. To go further, convert your result into lean body mass, compare it with the Army (AR 600-9) tape standard, or cross-check against your BMI.
Frequently asked questions
How accurate is the Navy body fat method?
- It's within about 3–4% of a DEXA/hydrostatic measurement for most people — good for tracking trends.
Where do I measure my waist and neck?
- Neck just below the larynx; men's waist at the navel; women's waist at the narrowest point and hips at the widest.
What is a healthy body fat percentage?
- Roughly 14–24% for men and 21–31% for women; "fitness" levels are lower (see the table).
Why does the women's formula need a hip measurement?
- Women carry more fat on the hips, so adding hip circumference improves the estimate.
Body fat % vs BMI — which is better?
- Body fat % distinguishes fat from muscle, so it's more individual than BMI.
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Disclaimer. This is a circumference-based estimate for healthy adults, not a clinical body-composition measurement or medical advice.