Health
Body fat percentage calculator
With a tape measure: measure neck, waist and, for women, hips. Your body fat percentage appears at once, with its category and how many kilos or pounds are fat and how many lean mass.
How body fat is estimated
The US Navy method (Hodgdon and Beckett, 1984) estimates body fat from circumferences, because fat is stored mostly around the abdomen and, in women, the hips. All it takes is a tape measure and a few seconds.
The American Council on Exercise categories for men are 2–5% essential, 6–13% athletes, 14–17% fitness, 18–24% average and 25% or more high; for women the thresholds are about eight points higher, because a share of fat is needed for hormonal functions.
If you also enter your weight, the calculation splits it into fat mass and lean mass: muscle, bone, organs and water. That is more useful than weight alone for following a training plan or a diet.
Common mistakes
- Pulling the tape too tight: it should sit snug without compressing.
- Measuring the waist at a different point each time: comparisons over time lose their meaning.
- Comparing the result with a bioimpedance scale: the two methods often disagree.
Frequently asked questions
What is a healthy body fat percentage?
Roughly 14–24% for men and 21–31% for women. Outside those ranges a more accurate check is worthwhile.
How accurate is this method?
The typical error is 3–4 percentage points. Accurate measurement needs skinfold calipers in expert hands or a DEXA scan.
Why do women also need the hips?
Because in women more fat is carried on the hips and buttocks, and the female formula takes it into account.
How this calculation works
Men: %fat = 495 / (1.0324 − 0.19077·log₁₀(waist − neck) + 0.15456·log₁₀(height)) − 450. Women: 495 / (1.29579 − 0.35004·log₁₀(waist + hips − neck) + 0.22100·log₁₀(height)) − 450, measurements in centimetres. Fat mass = weight × % / 100.
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