Body Fat Percentage Calculator
Estimate body fat percentage using the US Navy circumference method. Enter height, neck, and waist (plus hip for women). Supports metric and imperial units.
The US Navy method is an estimation tool, not a clinical measurement. Accuracy depends on correct measuring technique. Not medical advice — consult a professional for precise body composition assessment.
US Navy body fat method
The US Navy circumference method estimates body fat percentage from height, neck, and waist measurements (plus hip for women) using a logarithmic formula. For men: %BF = 495 / (1.0324 − 0.19077 × log10(waist − neck) + 0.15456 × log10(height)) − 450. For women the waist and hip measurements are combined. All measurements in this calculator are in centimetres internally; imperial inputs are converted before the formula is applied. If you enter your total body weight, lean mass (fat-free mass) is also shown.
Circumference-based methods are less accurate than DEXA or hydrostatic weighing but are far more accessible. Typical error range is ±3–4 percentage points compared to gold-standard methods. Measure at the same time of day for consistency, ideally in the morning before eating.
FAQ
Where is the waist measured? At the narrowest point of the torso, just above the navel. Keep the tape horizontal and do not suck in.
Where is the hip measured? At the widest point across the hips and buttocks. Used only for the female formula.