Body Fat Calculator
Estimate your body fat percentage with nothing but a tape measure. This calculator uses the U.S. Navy circumference method and shows healthy ranges for men and women.
Enter your measurements to estimate your body fat percentage.
This calculator uses the U.S. Navy circumference method, developed so body composition could be checked with nothing more than a tape measure. It combines your height with the circumference of your neck and waist (and hips for women) to estimate the percentage of your body weight that is fat.
Because it relies on where you carry size rather than weight alone, it captures something BMI cannot: two people at the same weight and height can have very different body fat. It won't match a lab scan exactly, but it's consistent and free.
- Neck: measure just below the larynx (Adam's apple), letting the tape slope slightly downward toward the front.
- Waist: at the level of the navel for men, and at the narrowest point of the torso for women.
- Hips (women): around the widest part of the buttocks.
- Keep the tape level and snug — firm against the skin but not squeezing it. Breathe normally and don't suck in.
- Measure at the same time of day each time (morning, before eating, is ideal) for the most comparable results.
Use the category as context, not a verdict. A "fitness" or "average" reading is perfectly healthy for most people, and chasing very low body fat can harm hormones, energy, and mood. If your goal is to lower body fat, combine a modest calorie deficit with enough protein — see the protein calculator — and resistance training to keep the weight you lose coming from fat, not muscle.
How does this body fat calculator work?
It uses the U.S. Navy circumference method, which estimates body fat percentage from your height and tape measurements: neck and waist for men, plus hips for women. No calipers, scales, or scans required — just a soft tape measure.
How accurate is the Navy body fat method?
The Navy method is accurate to roughly ±3–4% for most people, which is good for an at-home tape measurement. It's less precise than a DEXA scan or hydrostatic weighing, but far more accessible. Its real strength is consistency: measured the same way each time, it tracks changes reliably.
How do I measure correctly?
Use a flexible tape and measure on bare skin. Neck: just below the larynx, tape sloping slightly downward at the front. Waist: at the navel for men, at the narrowest point for women. Hips (women): at the widest point of the buttocks. Keep the tape snug but not compressing the skin, and don't hold your breath or suck in.
What is a healthy body fat percentage?
For men, roughly 14–24% is typical (6–13% is athletic). For women, roughly 21–31% is typical (14–20% is athletic). Women naturally carry more essential fat than men. Very low body fat isn't necessarily healthier — some fat is essential for hormones and organ function.
Why is my body fat different from my bathroom scale reading?
Smart scales use bioelectrical impedance, which is sensitive to hydration, meals, and skin temperature and can swing several percent between readings. The Navy tape method and impedance scales use completely different approaches, so they often disagree. Pick one method and track the trend rather than comparing across methods.
Should men and women use different ranges?
Yes. Women require more essential fat for reproductive and hormonal health, so healthy ranges sit several points higher than for men. This calculator applies sex-specific categories automatically and asks women for a hip measurement, which the formula requires.
How often should I remeasure?
Every 2–4 weeks is plenty. Body fat changes slowly, and measuring more often mostly captures noise. Measure under the same conditions each time — same time of day, same tape, ideally before eating — so the comparison is meaningful.
Is body fat percentage better than BMI?
For assessing body composition, yes — body fat percentage distinguishes fat from muscle, which BMI cannot. BMI is a quick screening tool based only on height and weight. If you're muscular, body fat percentage will give a far more accurate picture of your health and fitness.
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