Body Fat Calculator
Estimate your body fat percentage using the U.S. Navy circumference method and the BMI method, with body fat category, lean mass, and ideal body fat for your age.
Understanding Body Fat Percentage
This calculator's primary estimate uses the U.S. Navy method, developed by Hodgdon and Beckett in 1984. It estimates body fat from a handful of circumference measurements — waist and neck for men, plus hips for women — combined with height. It's not as accurate as clinical methods like hydrostatic weighing or DEXA scans, but it's far more practical and reasonably reliable for tracking changes over time, especially when the same person takes the measurements consistently.
As a secondary estimate, this calculator also converts your BMI into an approximate body fat percentage using age- and sex-specific formulas, with separate versions for children and teens. Because BMI doesn't distinguish muscle from fat, this method tends to be less accurate for very muscular or very lean individuals — the Navy method is generally considered the more reliable of the two.
The category ranges shown here (Essential, Athletes, Fitness, Average, Obese) follow the American Council on Exercise's classification, which differs for men and women since essential fat requirements differ by sex. The 'Ideal Body Fat for Given Age' figure comes from Jackson & Pollock's research, which found that healthy body fat percentages tend to rise gradually with age — so what's considered ideal at 25 is lower than what's considered ideal at 50.
Not all body fat is the same. Essential fat is the minimum needed for normal hormonal and reproductive function — typically 2–5% for men and 10–13% for women — and dropping below it is a real health risk, not a fitness goal. Storage fat, the fat these calculators mostly measure, includes both fat stored just under the skin and visceral fat around internal organs; visceral fat in particular is linked to a higher risk of heart disease, insulin resistance, and other complications, regardless of overall body weight.
Disclaimer
This calculator provides estimates only, based on standard formulas (the U.S. Navy method and a BMI-based method) applied to the measurements you enter. It is not a diagnostic tool and does not replace clinical methods like DEXA scans, hydrostatic weighing, or a physician's assessment.
Calclity is not a medical provider and this tool does not constitute medical advice. Body fat needs vary by individual, and dropping below the essential fat range can be dangerous. Consult a doctor or qualified health professional before making decisions based on these results, especially regarding weight loss, weight gain, or underlying health conditions.
Frequently Asked Questions
About this calculator
This body fat calculator estimates your body fat percentage two ways: the U.S. Navy method, which uses circumference measurements (neck, waist, and hips for women) combined with height, and a secondary BMI-based method. Results include your body fat category, fat and lean body mass, and how far you are from the ideal body fat percentage for your age based on Jackson & Pollock's research.
- U.S. Navy method — Estimates body fat from neck, waist, and (for women) hip measurements combined with height — no special equipment needed.
- BMI-based cross-check — Also computes a secondary body fat estimate from BMI, age, and sex, using separate formulas for children and teens.
- Gender-specific categories — Classifies your result into Essential, Athletes, Fitness, Average, or Obese using the American Council on Exercise's ranges, which differ between men and women.
- Ideal body fat for your age — Compares your result to age-adjusted ideal ranges from Jackson & Pollock's research and shows how much fat you'd need to lose or gain to reach it.
- Three unit systems — Switch between US units (feet/inches, pounds), metric units (cm, kg), or any custom combination of length and weight units.