Body fat percentage calculator
Body fat estimate from tape measurements.
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How it's calculated
The US Navy method estimates body fat from circumferences, because fat settles at the waist (and hips in women) while the neck tracks lean build. For men it is 86.010 × log(waist − neck) − 70.041 × log(height) + 36.76, with measurements in inches and base-10 logarithms; for women, 163.205 × log(waist + hips − neck) − 97.684 × log(height) − 78.387. Metric inputs are converted to inches first. Fat mass is weight times the percentage; lean mass is the rest. It is an estimate: measure first thing in the morning, tape snug but not tight, and track the trend rather than any single reading.
What is a healthy body fat percentage?
The American Council on Exercise ranges: for men, 6–13% athletes, 14–17% fitness, 18–24% average, 25% and over obese; for women, 14–20%, 21–24%, 25–31% and 32% and over. Essential fat, the minimum for health, is about 3% for men and 12% for women.
How accurate is the tape method?
Within about 3–4 percentage points of a DEXA scan for most people, which is similar to consumer bioimpedance scales and much better than BMI. It drifts for very muscular people and at the extremes. The useful part is the change over weeks, measured the same way each time.
Where exactly do I measure?
Neck: just below the Adam's apple, tape sloping slightly downward to the front. Waist: men at the navel, women at the narrowest point, relaxed, after a normal exhale. Hips (women): around the widest part of the buttocks. Stand straight, tape level and snug without compressing the skin.
Results are estimates for informational purposes only and are not financial, medical or legal advice.