Body Fat Estimator
Estimate body fat %, lean mass and fat mass using the U.S. Navy method.
Last updated 10/08/2026
Calculator
Body Fat Estimator inputs
Enter your height in centimetres, or feet/inches.
Stored only in this browser — never uploaded, no account required.
Manage My Service DetailsHow this works
What it means
An estimate of your body fat percentage, lean body mass and fat mass, using circumference measurements — plus which commonly-cited category your result falls into.
How it’s calculated
Uses the U.S. Navy circumference method (Hodgdon & Beckett, 1984): a formula based on height, neck and waist (plus hip for women). Category thresholds use the commonly-cited American Council on Exercise (ACE) body-fat ranges.
Common Defence use cases
A more composition-aware alternative to BMI, and tracking body fat percentage changes over time.
Formula
Male: BF% = 495 ÷ (1.0324 − 0.19077×log₁₀(Waist − Neck) + 0.15456×log₁₀(Height)) − 450
Female: BF% = 495 ÷ (1.29579 − 0.35004×log₁₀(Waist + Hip − Neck) + 0.22100×log₁₀(Height)) − 450
Lean Body Mass = Weight × (1 − BF% ÷ 100)
Fat Mass = Weight × (BF% ÷ 100)Assumptions
- Estimate only — not a precise body composition measurement (e.g. DEXA scan or skinfold callipers) and not a Defence-specific standard.
- Uses the U.S. Navy circumference method — a commonly accepted civilian estimation formula (Hodgdon & Beckett, 1984), not an official military standard.
- Category thresholds use the commonly-cited American Council on Exercise (ACE) body-fat-percentage ranges, by gender — a civilian reference, not a Defence-specific one.
- Accuracy depends on careful, consistent measurement technique for waist, neck and (for women) hip.
- Height can be entered in centimetres or feet/inches — enter one or the other, not both.
Example calculations
Male, Height 175 cm, Weight 75 kg, Waist 85 cm, Neck 38 cm
Estimated Body Fat ≈16–18% (Fitness/Acceptable range)
Female, Height 165 cm, Weight 60 kg, Waist 70 cm, Neck 32 cm, Hip 95 cm
Estimated Body Fat ≈22–25% (Fitness/Acceptable range)