Body Fat Calculator

What is a body fat calculator?

A body fat calculator estimates your body fat percentage using the US Navy circumference method — measuring waist, neck, and (for women) hips rather than using electrical impedance or a DEXA scan. It gives a field-usable estimate in under a minute.

How this calculator works

• Enter your sex, height, weight, and the required circumference measurements.
• For men it uses waist and neck; for women it adds hip circumference.
• The Navy formula converts those taped measurements into a body fat percentage.
• It also shows fat mass, lean body mass, and a broad category label.

How to use the result

1. Measure carefully: waist at the narrowest point, neck below the larynx, hips at the widest point — tape flat against skin, not pulled tight.
2. Weigh in consistently (morning, after bathroom, before food) because weight drives the fat-mass figure.
3. Track trends, not single readings — a 1–2% swing from hydration is normal. Compare month to month.
4. Use body fat as a complement to scale weight: if fat % drops while weight holds, you’re recomping.

How accurate is the Navy body fat method?

Within about 2–4 percentage points of DEXA for most adults, which makes it one of the best no-equipment estimates. Accuracy depends on measurement technique — consistent tape placement and tension matter more than the formula itself. Athletes and very lean individuals can see larger gaps.

Common mistakes

• Measuring over clothing. Even thin fabric adds meaningful inches to the tape.
• Using the wrong landmarks. The waist is the narrowest point, not the navel; the neck is below the larynx, not the jawline.
• Judging health on body fat alone. Muscle, bone density, and distribution all matter — pair it with the BMI calculator for the fuller picture.

Body fat connects directly to your training and nutrition targets — the BMR calculator sets your calorie baseline, the TDEE calculator scales it to your activity, and the macro calculator turns the target into protein, fat, and carbs.