Body Fat Calculator
Two ways to estimate body fat: the Navy tape method (accurate) and the BMI shortcut (quick) — with category bands for each.
How to use
- Pick your sex, then enter age, height (cm) and weight (kg).
- Add neck and waist measurements — hip only for women.
- Read the Navy estimate, its category, and the BMI-based estimate below.
Frequently asked questions
How does the Navy body fat method work?
It estimates body fat from circumference ratios: neck against waist for men, and against waist plus hip for women, scaled by height. It was validated against underwater weighing and is the US military’s standard screening method.
Where exactly should I measure?
Neck: below the larynx, tape sloping slightly down at the front. Waist: at the navel for men, at the narrowest point for women. Hip (women): the widest point of the glutes. Keep the tape snug, not compressing.
What are healthy body fat ranges?
Using ACE categories: men span roughly 2–5% essential, 6–13% athletes, 14–17% fitness, 18–24% average; women run about 10–12 points higher at each band. The calculator shows your band automatically.
Why is there also a BMI-based estimate?
The Deurenberg equation (1.2×BMI + 0.23×age − 10.8×sex − 5.4) needs no tape at all and is useful as a sanity check. It is less accurate than the Navy method but only requires age, sex, height and weight.
How accurate is any home body fat estimate?
Expect ±3–4% error even with careful technique. For tracking, what matters most is consistency — same tape, same spots, same time of day — so trends beat absolute numbers.