Body Fat Calculator
How the U.S. Navy method works
The Navy circumference method estimates body fat from the ratio of your waist (and hips for women) to your height and neck. A larger waist relative to height suggests more fat stored around the middle, while a thicker neck reflects a larger frame. The formulas convert these log-scaled ratios into a percentage through a curve fitted to laboratory measurements. Men need only height, neck, and waist; women also need a hip measurement.
Reading your result
Body fat percentage splits your weight into fat mass and lean mass (muscle, bone, organs, and water). Athletes typically carry less fat than the average range, but some fat is essential for health — around 2–5% for men and 10–13% for women. Unlike BMI, the tape method responds to where you carry weight, so it often labels muscular people more fairly. Track the trend over time rather than chasing a single number. This estimate is not medical advice; ask a professional for a full assessment.
Frequently Asked Questions
How do I take the measurements correctly?
Use a flexible tape that sits flat against the skin without squeezing. Measure the neck just below the larynx, the waist at the navel (men) or at the narrowest point (women), and the hips at their widest point. Take each measurement twice and average the two.
How accurate is the Navy tape method?
Studies typically find it within about 3–4 percentage points of DEXA scans for most people. Consistency matters most: measuring the same way each time makes trends reliable even if the absolute number is slightly off.
Why is there a healthy range instead of one ideal number?
Healthy body fat varies with age, sex, and athletic goals. The categories shown here mirror widely used fitness bands, and the Jackson & Pollock ideal line shifts with age, but a healthcare provider can interpret your number in the context of your overall health.