Body-fat percentageBody fat %
The share of your body weight that is fat rather than lean tissue.
Body fat percentage is the share of your total weight that is fat rather than lean tissue. It answers the question BMI cannot: two people at the same height and weight can differ enormously in how that weight is composed.
Not all of it is optional. Essential fat, in the brain, nerves, bone marrow and organs, sits at roughly 3% in men and 12% in women, the difference being sex specific fat that supports reproductive function. Below those levels is not lean, it is dysfunctional, and in athletes it is a recognised route into relative energy deficiency in sport.
Where fat sits matters more than the total. Visceral fat around the organs tracks with insulin resistance and cardiovascular risk far more closely than subcutaneous fat does, which is why a waist measurement often tells you more about health than a body fat estimate does.
Measuring it is harder than the numbers suggest. DEXA is the practical reference and still varies between machines and visits. Bioimpedance scales are strongly affected by hydration and can swing several points across a day. Skinfolds are decent in trained hands and poor otherwise. Circumference equations, including the Navy formula our calculator uses, are cheap and approximate.
Because of that, the trend from one consistent method is worth far more than a single number from any method. Comparing a DEXA result with a scale reading is comparing two different measurements, and the difference tells you about the devices rather than about you.
The photographs online are worse than the devices. Images labelled with a body fat percentage are usually posed, lit and unverified, and they set expectations that the actual measurements do not support.
In practice, pick one method, use it the same way, watch the direction, and pair it with a waist measurement. Our body fat calculator and waist to height ratio calculator cover both.