Body Fat Calculator
Enter valid measurements — waist must be greater than neck (and for women, waist+hip greater than neck).
This result is outside the physiologically typical range — the US Navy method is known to be less reliable for some body shapes. Double-check your measurements, or try a different method (DEXA scan, calipers) for a more reliable number.
Measure neck just below the larynx, waist at the navel, and (for women) hips at the widest point. This circumference-based method is a widely-used field estimate, not as accurate as a DEXA scan or hydrostatic weighing.
Free body fat calculator using the US Navy circumference method — with a plausibility check that flags results outside the physiologically typical range, instead of confidently showing a number that may be unreliable for your body shape.
How it works
- Enter your sex and height
- Measure neck, waist, and (for women) hip circumference
- See your estimated body fat percentage
Frequently asked questions
How accurate is the US Navy method?
It's a widely-used field estimate, generally within a few percentage points of more precise methods like DEXA scans for most people — but it can be less reliable for people with body shapes far from average, which is why this calculator flags results outside a physiologically plausible range.
Where exactly do I measure?
Neck: just below the larynx (Adam's apple). Waist: at the navel. Hip (women only): at the widest point of the hips/buttocks. Keep the tape snug but not compressing the skin.
Related tools
From the blog
Update history
- 2026-09-03 Height, neck, and waist are now sliders instead of number fields, and the sex toggle shows an icon for each option.
- 2026-09-01 Changed: brighter chart segment colors, and the result percentage now matches its category color for a clearer at-a-glance read.
- 2026-09-01 Added: a visual chart showing where the result falls across ACE body fat categories (Essential fat / Athletes / Fitness / Average / Obese), with a marker on the result and a category label.
- 2026-09-01 Added: an inch/cm unit toggle for height, neck, waist, and hip measurements, defaulting to inch. Values convert automatically when switching units.
- 2026-09-01 Added: a cover image — used as the card thumbnail, social share image, and blog title image.
- 2026-09-01 Launched: US Navy method body fat calculator with a plausibility-range warning for results outside the physiologically typical range. Entirely client-side, reuses the body composition engine.