Body Fat Estimate Calculator

This calculator needs JavaScript. Your browser has JavaScript switched off, so the numbers cannot be worked out here. The explanation below is still readable, and you can read the linked guides instead.

Body fat estimate calculator

This calculator gives an estimate of body fat percentage from a tape measure, using the US Navy circumference method. It is an estimate with a margin of error, never a medical measurement.

Sex

Height (cm)

Neck (cm, at the narrowest point)

Waist (cm, at the belly button)

Enter your measurements to see an estimated body fat percentage.

What this result means

This uses the US Navy circumference method. It takes your height, neck, and waist, and for women also the hip, then works out an estimate from those numbers. The formula is:

Men: 495 divided by (1.0324 minus 0.19077 times log10 of waist minus neck, plus 0.15456 times log10 of height) minus 450. Women use a different set of constants that also include the hip.

The result is an estimate, not a measurement. Expect a margin of about plus or minus 3 to 4 percent compared with a proper scan. Measure the neck at the narrowest point, the waist at the belly button, and the hip at the widest point, with the tape snug and level.

Limits and when to see a doctor

This is never a medical measurement. It is a rough estimate from a tape measure, and it can be quite wrong for very muscular people, very lean people, older adults, and anyone with an unusual body shape. It is not a diagnosis of anything. If you want an accurate body fat figure, or if you have a health concern about your weight or body composition, ask a doctor or a qualified professional.