Body Fat Calculator
Estimate your body fat percentage with the US Navy tape-measure method, plus fat and lean mass.
About the Body Fat Calculator
The US Navy method estimates body fat from height and a few circumferences. It was validated against underwater weighing and is usually within about 3–4 percentage points, which makes it one of the best options without lab equipment.
Measure on bare skin with a flexible tape: men at the navel and neck; women at the narrowest waist, the neck and the widest part of the hips. Keep the tape level and snug but not tight.
The formula
Men: %BF = 495 ÷ (1.0324 − 0.19077·log₁₀(waist − neck) + 0.15456·log₁₀(height)) − 450
- Women
- 495 ÷ (1.29579 − 0.35004·log₁₀(waist + hip − neck) + 0.22100·log₁₀(height)) − 450
- Units
- centimetres
Body fat categories (American Council on Exercise)
| 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% + |
Worked example
Example: Body fat (US Navy method) = 14.6%
- Inputs: Units: lb / ft; Sex: Male; Age: 39 years; Height: 6 ft; and: 10 in; Weight: 180 lb; Waist (at the navel): 37 in; Neck (below the larynx): 17 in.
- Formula: Men: %BF = 495 ÷ (1.0324 − 0.19077·log₁₀(waist − neck) + 0.15456·log₁₀(height)) − 450
- Result: Body fat (US Navy method) = 14.6%
- Fat mass: 26 lb
- Lean mass: 154 lb
- Category (ACE): Fitness
Things to keep in mind
- This is an estimate for general information, not medical advice. Talk to a doctor or other qualified professional about your health.
- Accuracy is lower for very muscular people and for people with obesity.
Questions people ask
How accurate is this?
Typically within 3–4% of lab methods like DEXA, with consistent measuring.
What is a healthy body fat percentage?
Roughly 10–20% for men and 18–28% for women is common for health; athletes are lower.