Body fat percentage calculator

How to use the body fat percentage calculator

1. Sex. Pick male or female. The two use different formulas.
2. Units. Pick centimeters or inches. Numbers you have already typed are converted for you.
3. Height. Stand straight, without shoes.
4. Neck. Measure just below the larynx. Keep the tape snug but not tight.
5. Waist. Men measure level with the navel. Women measure at the narrowest point. Stay relaxed and do not pull your stomach in.
6. Hip. Women only. Measure around the widest part of the hips.

The big number is your estimated body fat. Under it you see which category it falls in and the range for that category.

Please note: this is an estimate from tape measurements, not a medical assessment. It cannot diagnose anything. Speak to a doctor before you make any health decision based on it.

The US Navy method formula

The US Navy method estimates body fat from a few circumference measurements. The formulas use inches. If you enter centimeters, the body fat calculator divides each number by 2.54 first.

Men: body fat % = 86.010 × log10(waist − neck) − 70.041 × log10(height) + 36.76

Women: body fat % = 163.205 × log10(waist + hip − neck) − 97.684 × log10(height) − 78.387

Worked example

A man is 178 cm tall, with a 38 cm neck and an 86 cm waist.

• Waist minus neck: 86 − 38 = 48 cm. In inches: 48 ÷ 2.54 = 18.898.
• Height in inches: 178 ÷ 2.54 = 70.079.
• log10(18.898) = 1.2764, and 86.010 × 1.2764 = 109.78.
• log10(70.079) = 1.8456, and 70.041 × 1.8456 = 129.27.
• 109.78 − 129.27 + 36.76 = 17.27, so about 17.3%.

For men that sits at the top of the fitness range in the table below.

Body fat categories

These are the commonly cited ranges from the American Council on Exercise. The calculator uses them to name your category.

Category	Women	Men
Essential fat	10 to 13%	2 to 5%
Athletes	14 to 20%	6 to 13%
Fitness	21 to 24%	14 to 17%
Average	25 to 31%	18 to 24%
Obese	32% and above	25% and above

The ranges are a general guide. They do not account for age, build or medical history.

Getting a reliable reading

• Use a soft tape. Keep it flat against the skin and level all the way round. Do not let it dig in.
• Measure twice. Take each measurement two or three times and use the average. A small slip of the tape moves the result.
• Same time, same way. If you track the number, measure at the same time of day and in the same spots each time.
• Check the units. A result that looks far off usually means inches were typed as centimeters, or the other way round.
• Know the limits. The method only sees your outline. It cannot tell muscle from fat, so very muscular people and people with an unusual build can get a misleading number.

Tape methods are less exact than clinical tests such as a DEXA scan. Treat the result as a rough guide and ask a doctor what it means for you.

Tracking over time? Use days between dates to count the days since your last measurement. The age calculator gives your exact age if a form asks for it.

How this calculator was checked

Built by Rasel Hakkani, WordPress developer at Swift Web Dev. The results were compared with a separate calculation of the published formulas, for men and women, in centimeters and inches. It is an estimate from tape measurements, not a medical assessment.

Sources

• Hodgdon and Beckett, Naval Health Research Center, 1984: Prediction of percent body fat for U.S. Navy men and women from body circumferences and height (the source of the formulas)
• American Council on Exercise body fat categories (the ranges in the table)

Last checked: October 2026. Found a wrong answer? Tell us and we will fix it.