Body Fat Calculator
Estimate body fat, fat mass, and lean mass using height and waist measurements with the published Relative Fat Mass method.
Published by Reeve Editorial Team · Methods and sources updated
Estimated body fat · RFM method
36.0%
A population estimate from height and waist; individual error can be substantial.
Estimated fat mass
25.2 kg
Estimated lean mass
44.8 kg
Includes water, organs and bone as well as muscle.
Inputs stay in this tab. Saving keeps a copy on this device until you reset or clear it.
These adult screening estimates do not apply during pregnancy. Body composition, ancestry, age, medical history, and measurement technique can change how a result should be interpreted.
How this tool works
RFM = 64 − 20 × height ÷ waist + 12 for the female reference (no added term for the male reference). Height and waist must use the same units. Measure the waist at the top of the hip bone, consistent with the study's measurement protocol.
Fat mass is entered weight multiplied by estimated fat percentage; lean mass is the remainder. Lean mass includes water, organs, bone and muscle. This adult population equation is not a body scan. The tool declines estimates outside 0–65% rather than silently clipping them.
Sources
Frequently asked questions
Is this the U.S. Navy method?
No. This tool uses RFM, which needs height and waist. Different methods use different measurements and should not be treated as interchangeable.
How should I use changes in the result?
Repeat the same measurement method under similar conditions. Small changes may reflect tape placement or normal variation rather than a true change in fat mass.