Body Fat Calculator – US Navy Method Percentage
Estimate your body fat percentage with the US Navy circumference method. Measure neck, waist and (for women) hip with a tape measure. This method correlates well with DEXA and hydrostatic weighing—better than BMI for tracking body composition during weight loss or muscle gain. Works for fitness enthusiasts and general health tracking.
Body Fat Calculator
Estimate body fat percentage using the US Navy method. Measure waist, neck and (for women) hip with a tape measure. More accurate than BMI for tracking body composition.
How the US Navy body fat formula works
The Navy method uses logarithmic equations based on circumference ratios:
Men: 86.01×log₁₀(waist−neck) − 70.041×log₁₀(height) + 36.76
Women: 163.205×log₁₀(waist+hip−neck) − 97.684×log₁₀(height) − 78.387
All measurements in centimetres. The formulas were developed by the Naval Health Research Center and validated against gold-standard methods. Best accuracy for 15–30% body fat; may overestimate for very lean athletes and underestimate for obesity.
Body composition and why it matters
Body fat percentage measures the proportion of fat to total body weight. Unlike BMI, it distinguishes between muscle and fat—two people with the same BMI can have very different body fat. Athletes often have "high" BMI from muscle but low body fat. The Navy method uses circumferences to estimate subcutaneous and visceral fat distribution.
Use this calculator alongside the BMR and calorie calculators to track progress during diet and exercise. For pregnancy planning, try the pregnancy due date and ovulation calculators. All tools run locally; no data is stored.