Body composition tool
Body-Fat Calculator
Use circumference measurements to estimate body-fat percentage with the US Navy method.
Understanding your body-fat percentage
Body-fat percentage is the share of your total weight that is fat rather than muscle, bone and water. This tool estimates it with the US Navy circumference method, which uses a few tape measurements instead of special equipment.
How to use it
- 1Measure your waist, neck and height in centimetres; women also measure the hip.
- 2Use a tape that is snug but not tight, and measure at the same points each time.
- 3Select your gender and enter the measurements.
- 4Select Calculate to see your estimated body-fat percentage.
How it helps your fitness
Body-fat percentage shows what the scale hides: it can fall even when your weight holds steady, because you are gaining muscle and losing fat at the same time. Tracking it gives a clearer picture of body composition than weight alone.
What the numbers mean
- Body-fat %
- The proportion of your body weight made up of fat.
- Athletic — men ~6–13%, women ~14–20%
- Lean and visibly defined; typical of trained athletes.
- Fitness / average — men ~14–24%, women ~21–31%
- A healthy range for most active adults.
- Waist, neck, hip
- The circumference measurements the formula uses; the waist reading matters most.
Keep in mind
The tape method is a convenient estimate, not a lab measurement, and can be off by a few percent. Its real value is the trend, so measure the same way, at the same time of day, every few weeks.