Body Fat Percentage Calculator
Body fat percentage is the proportion of your total body mass that is made up of fat tissue. It is a more informative health marker than weight alone because two people of identical weight and height can have very different health profiles depending on how much of that weight is muscle, bone, and fat. The US Navy circumference method, developed for military fitness assessments, estimates body fat from simple tape measurements: neck, waist, and (for women) hips, combined with height. It requires no specialist equipment, can be done at home, and is accurate to within a few percentage points of gold-standard DEXA scanning for most people. The method uses logarithmic calculations to adjust for the cylindrical shapes of body segments. Enter all measurements in centimetres. Women should include the hip measurement. All measurements should be taken with a flexible tape held snug but not compressing the skin, at the end of a normal breath.
Formula
Male: BF% = 86.010 * log10(abdomen - neck) - 70.041 * log10(height) + 36.76
Female: BF% = 163.205 * log10(waist + hip - neck) - 97.684 * log10(height) - 78.387
All measurements in centimetres.
Body Fat Percentage Calculator: frequently asked questions
How accurate is the US Navy body fat method?
The US Navy circumference method has a margin of error of approximately 3 to 4 percentage points compared with DEXA scanning. It tends to overestimate body fat in very lean individuals and underestimate it in people who carry fat in areas not captured by the measurements. It is a useful screening tool rather than a clinical measurement.
Where do I measure my waist for this calculator?
For males, measure the waist at the level of the navel. For females, measure at the narrowest point of the abdomen, typically just above the navel. The tape should be horizontal, snug but not compressing the skin, and the measurement taken at the end of a normal exhale.
What are healthy body fat percentage ranges?
According to the American Council on Exercise, essential fat is 2 to 5% for men and 10 to 13% for women. Athletes range from 6 to 13% (men) and 14 to 20% (women). Fitness ranges are 14 to 17% (men) and 21 to 24% (women). Acceptable is 18 to 24% (men) and 25 to 31% (women). Above these ranges is considered obese.
How do I measure my neck circumference?
Measure the neck below the larynx (Adam's apple), with the tape perpendicular to the long axis of the neck. Do not tilt your head. The tape should be snug but not tight. Take three measurements and use the average.
What is the difference between the male and female formulas?
The male formula uses only the abdomen and neck circumferences because men store most body fat in the midsection. The female formula also includes the hip measurement because women distribute fat more in the hip and thigh area. Both formulas use height as a normalising variable.
Official sources
- Hodgdon JA, Beckett MB. (1984). "Prediction of percent body fat for U.S. Navy men and women from body circumferences and height." Report No. 84-29. Naval Health Research Center.
- American Council on Exercise: Body Fat Categories
Reviewed by the CalculatorHub team, edited by James Graham, 14 June 2026. See our methodology.