Body fat percentage describes the proportion of body weight that is fat, while lean mass includes muscle, bone, organs, and body water. This calculator combines a U.S. Navy circumference method with a BMI-based estimate and displays a central result to provide useful context when a laboratory or imaging method is not available.
Tape-based estimates are highly dependent on measurement technique. Take measurements at the same locations, with the tape level and snug rather than compressing the skin, and repeat them under similar conditions. Hydration, posture, digestion, and normal fluid shifts can move the result, so use consistent trends rather than treating a single percentage as a diagnosis or a precise composition measurement.
It uses body measurements for a U.S. Navy-style estimate and combines that with a BMI-based estimate. The resulting value is intended for general tracking, not as a substitute for DEXA or other validated clinical assessment.
Measure consistently with a flexible tape held level and comfortably snug, without pulling it into the skin. Use the same landmarks and timing each time, and take more than one reading when possible.
Water retention, food volume, posture, tape placement, and measurement tension can change the inputs. A sudden shift is more likely to reflect short-term variation than a rapid change in body composition.
No. Very low levels can affect energy, hormones, recovery, and other aspects of health. A suitable range depends on the individual, and symptoms or aggressive dieting warrant professional guidance.