Understanding circumference-based body-fat estimates
This calculator uses the U.S. Navy circumference method to estimate body-fat percentage from height and body measurements. It is an estimate based on a prediction equation, not a direct measurement of body composition. Small differences in tape placement, posture, breathing, or measurement technique can change the result.
Use consistent measurements
Follow the input units shown on the page and use a flexible tape without pulling it tightly into the skin. If you compare measurements at different times, use the same method and measuring locations each time. A change in the estimate does not by itself prove a corresponding change in body fat.
Circumference equations have individual prediction error and should not be used to diagnose health or determine whether someone meets a medical standard. A published evaluation of circumference-based methods reported meaningful limitations in individual predictions; see the study indexed by PubMed. For health concerns, ask a qualified healthcare professional to interpret any body-composition measure.
Tips for accurate results
Body fat formulas based on tape measurements need careful technique: measure at the same points each time, keep the tape snug but not compressing the skin, and take each measurement twice. Because the result is an estimate, track the trend over weeks using identical conditions rather than reacting to a single reading.
Common mistakes and limits
Measurement-based estimates can be off by several percentage points compared with methods such as DEXA scans. Hydration, recent meals, and body shape all affect the result. Healthy ranges differ by age and sex, and very low values are not automatically better.