Calculator
Are you losing fat or muscle?
Two weigh-ins with your weight and bodyfat. See how much of the change was fat and how much was lean mass.
First weigh-in
Latest weigh-in
How it works
Fat mass is your weight times your bodyfat. Lean mass is the rest: muscle, water, organs and bone. The change in each between two weigh-ins is the split.
A home scale finds bodyfat by sending a small current through you, so water moves its number. In a 2022 test of 14 home devices in 73 adults, a single measurement missed a lab method by about 3 to 13 points, depending on the model. When 37 of them came back 12 to 16 weeks later, the error on the change was about 2 to 3 points. So compare weigh-ins a month or more apart, each the average of a week of mornings.
More calculators
Weigh in each morning on a Withings or any Apple Health scale and Gyroscope logs your weight and bodyfat on its own, free on any plan. Open Gyroscope
