Estimate body fat percentage from height, weight, neck, waist, and hip measurements using the US Navy circumference method.
Body fat % = US Navy circumference equationThe US Navy body fat method estimates body fat percentage from circumference measurements. Men use height, neck, and waist. Women use height, neck, waist, and hip. The calculator also converts the percentage into estimated fat mass and lean mass.
| Symbol | Variable | Description |
|---|---|---|
| waist | Waist circumference | Measured around the abdomen at a consistent landmark. |
| neck | Neck circumference | Measured below the larynx with the tape level. |
| hip | Hip circumference | Used for female estimates and measured at the widest hip point. |
Measure consistently
Use a flexible tape, keep it level, and do not pull it tight enough to compress skin.
Enter required circumferences
Men need neck and waist. Women also need hip circumference.
Compare trends
Use the estimate to monitor change over time rather than treating one reading as exact.
A body fat calculator is most useful for trend tracking. If weight stays the same but waist decreases, body composition may be improving. If body fat percentage changes rapidly from one entry to the next, recheck the tape placement before changing your plan.
Body fat ranges differ by sex, age, training status, and health context. The category shown here is a broad fitness reference, not a medical diagnosis.
| Category | Men | Women |
|---|---|---|
| Essential | 2-5% | 10-13% |
| Athlete | 6-13% | 14-20% |
| Fitness | 14-17% | 21-24% |
| Average | 18-24% | 25-31% |
| High | 25%+ | 32%+ |
Small measuring errors can shift a body fat percentage estimate. Take each circumference twice, use the same tape, and measure at the same time of day. For higher accuracy, compare this result with skinfolds, DEXA, or professional assessment when available.