Body Fat Calculator
Estimate your body fat percentage with the US Navy circumference method. It uses your height plus neck and waist measurements, and hip for women.
US Navy method. Measurements in inches.
How to use the Body Fat Calculator
- Enter your numbers in the Body Fat Calculator above.
- Press the Calculate Body Fat button to see the result.
- To try other numbers, change any value and press the button again.
The US Navy body fat formula
Men: BF% = 86.010·log10(waist − neck) − 70.041·log10(height) + 36.76 · · · Women: BF% = 163.205·log10(waist + hip − neck) − 97.684·log10(height) − 78.387
All measurements in inches. The US Navy developed these equations in 1984 for military fitness screening. The result is an estimate from tape measurements, and a lab scan of the same person can read several points higher or lower. The FAQ below gives the error one study measured against DXA scans.
Worked example
A man with 70" height, 34" waist, 15" neck: BF% = 86.010·log10(19) − 70.041·log10(70) + 36.76, which the calculator shows as 17.51%, in the Fitness band. With a 36" waist and the same other values it shows 21.25%, in the Average band.
Frequently asked questions
What is a healthy body fat percentage?
The calculator does not say which result is healthy for you. It puts your result in one of five bands. For men, essential fat is under 6%, athletes 6% to under 14%, fitness 14% to under 18%, average 18% to under 25%, and obese 25% or more. For women, essential fat is under 14%, athletes 14% to under 21%, fitness 21% to under 25%, average 25% to under 32%, and obese 32% or more. The band is read from the percentage as shown, rounded to 2 decimal places.
How accurate is the Navy method?
A 2023 study in Frontiers in Physiology by Foulis and colleagues compared these equations with DXA scans in 926 men and 481 women starting US Army basic training. The standard error of the estimate was 3.4 percentage points of body fat for men and 4.1 for women. The tape result also averaged 6 points below the DXA reading in both sexes. Those recruits were young adults, so the error at other ages may differ. Treat your result as an estimate.
Is there a more accurate method?
DXA scans and underwater weighing are the lab methods researchers use as the reference when they test tape equations. The Bod Pod is a third lab option. Each needs a visit to a clinic or lab. Skinfold calipers work at home but take practice to read consistently.