How do I measure body fat?
Pick one method and keep using it: every home method is off by several percent, but the direction it moves over a month is reliable.
There is no cheap method that gives you a true number. A tape measure is off by a few percent in a known direction, body fat scales swing with how hydrated you are, calipers depend on who is pinching, and even a DXA scan shifts between machines and between visits.
What all of them do well is track change. Measure under the same conditions, first thing in the morning after the toilet, before eating or drinking, and compare months rather than days. Add a photo in the same light and a tape measure around your waist, which is the honest pair: if the waist is shrinking and the lifts are holding, it is going the right way, whatever number the scale invents.
Run the numbers
Compare
Sources
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- Potter, A.W. et al. (2022). Circumference-based predictions of body fat revisited: preliminary results from a US Marine Corps body composition survey. Front Physiol 13. 609 fit Marines against DXA: the tape method read about 2.5% low in men and high in women, with a spread of roughly 4% around that.
- Ode, J.J. et al. (2007). Body mass index as a predictor of percent fat in college athletes and nonathletes. Med Sci Sports Exerc 39(3). Why weight-based shortcuts fail on trained people: BMI flagged muscular athletes as overweight far too often.