Body Fat Calculator
Estimate body fat percentage using the US Navy tape measurement method.
🔢
Body Fat Calculator
Use the formula and worked example below to calculate manually.
Overview
This body fat calculator estimates your body fat percentage using the U.S. Navy circumference method — a tape-measure-based approach that correlates well with DEXA scans without requiring expensive equipment.
How to use this calculator
- Select your gender.
- Enter your height, neck circumference, waist circumference, and (for women) hip circumference.
- All measurements at the described reference points.
- The calculator shows your estimated body fat percentage and category.
Understanding the inputs & results
Body fat %
The proportion of your total body weight that is fat mass.
Neck circumference
Measured just below the larynx (Adam's apple), perpendicular to the neck axis.
Waist circumference
Measured at the narrowest point (men) or at the navel level (women).
Hip circumference (women)
Measured at the widest point of the hips.
Essential fat
The minimum fat needed for health — ~3% men, 12% women.
The formula
U.S. Navy body fat formula
Men: %BF = 86.01×log10(waist−neck) − 70.041×log10(height) + 36.76 | Women: %BF = 163.205×log10(waist+hip−neck) − 97.684×log10(height) − 78.387
All measurements in cm. This empirical formula is validated against hydrostatic weighing and is accurate to within ±3.5% for most individuals.
Worked example
Male, 175 cm height, 35 cm neck, 85 cm waist.
- %BF = 86.01 × log10(85−35) − 70.041 × log10(175) + 36.76.
- = 86.01 × 1.699 − 70.041 × 2.243 + 36.76 ≈ 21.6%.
✓ Estimated body fat ≈ 21.6% (Fitness category for men).
Frequently asked questions
This calculator provides an estimate only. Body fat percentage varies with hydration, meal timing, and measurement technique. Not a substitute for medical body composition analysis.