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Your body fat

Find out your body composition from circumference measurements.

ft
in
lb
in
in
in
26.9%
Healthy
Fat mass
38.0 lb
Lean (LBM)
103.1 lb
Ideal range 21–33% · you're in the ideal range

What is body fat percentage?

Body fat percentage is the value showing what portion of your total body weight is fat tissue. The rest is lean body mass (LBM): muscle, bone, water and organs.

This ratio reveals what weight alone cannot: of two people at the same weight, one may be more muscular and the other fatter. So it is more telling than weight for understanding body composition.

Calxin estimates this ratio with the U.S. Navy method, evaluating neck, waist and (for women) hip circumference together with height. No device is needed — a tape measure is enough. The healthy range varies by sex.

How is it calculated?

Body fat percentage shows what portion of your total weight is fat; the rest is lean mass (muscle, bone, water, organs).

Calxin uses the classic U.S. Navy circumference formula. Neck and waist (plus hip for women) are evaluated together with height:

MALEFat% = 86.010 × log₁₀(waist − neck) − 70.041 × log₁₀(height) + 30.30
FEMALEFat% = 163.205 × log₁₀(waist + hip − neck) − 97.684 × log₁₀(height) − 104.912

All measurements are in centimetres and the logarithm is base 10.

For men, measure the abdomen at navel level; for women, measure the waist at its natural (narrowest) point. Measure the hips at the widest point and the neck just below the larynx. Keep the tape parallel to the floor and don’t compress the skin.

This circumference-based method is practical but produces an estimate. Calipers, bioelectrical impedance and especially a DEXA scan give more precise results; DEXA is considered the gold standard in this field.