Body composition
Body fat calculator (US Navy method)
Estimate your body fat percentage from a tape measure: neck and waist for men, neck, waist and hips for women, plus your height. The calculator uses the US Navy circumference equations and compares the result with healthy body fat ranges for your sex and age from a peer-reviewed study that linked body fat to the BMI cut-offs.
Enter your values above to see your result and what it means.
What is a healthy body fat percentage?
Gallagher and colleagues (American Journal of Clinical Nutrition, 2000) measured body fat with reference methods in 1,626 adults and worked out which body fat levels go with the WHO BMI cut-offs of 18.5, 25 and 30. The healthy range is the span between the first two. Women carry more body fat than men at the same BMI, and body fat at a given BMI rises with age, so the ranges differ by both. The table shows the values for white adults; the study found Asian adults had higher body fat at the same BMI, so their healthy ranges sit higher.
| Sex and age | Below healthy | Healthy range | Above healthy | Obesity range |
|---|---|---|---|---|
| Women 20-39 | under 21% | 21-32.9% | 33-38.9% | 39% or more |
| Women 40-59 | under 23% | 23-34.9% | 35-40.9% | 41% or more |
| Women 60-79 | under 25% | 25-37.9% | 38-42.9% | 43% or more |
| Men 20-39 | under 8% | 8-20.9% | 21-25.9% | 26% or more |
| Men 40-59 | under 11% | 11-22.9% | 23-28.9% | 29% or more |
| Men 60-79 | under 13% | 13-24.9% | 25-30.9% | 31% or more |
How to measure body fat with a tape measure
Use a tape that does not stretch, held snug on bare skin without pressing in, and take each measurement two or three times. Neck: just below the larynx (Adam's apple). Waist for men: around the abdomen at the level of the navel. Waist for women: at the narrowest point of the torso. Hips (women): around the widest part of the buttocks, tape level with the floor. Stand relaxed and measure the waist at the end of a normal breath out, without pulling the stomach in. Height without shoes.
How the US Navy body fat formula works
Hodgdon and Beckett at the US Naval Health Research Center published the equations in 1984, and all US military services later agreed to use them. With all measurements in inches, men: 86.010 × log10(waist − neck) − 70.041 × log10(height) + 36.76. Women: 163.205 × log10(waist + hip − neck) − 97.684 × log10(height) − 78.387. Example: a man 70 in tall with a 15 in neck and a 34 in waist comes out at about 17.5%. The calculator converts centimetres to inches before applying the formula.
How accurate is the Navy method?
It is a screening estimate. Compared with DXA scans, the equations read low on average: by about 6 percentage points in a 2023 study of 1,407 Army recruits, and with a typical error of about 6 points in men and 4 in women in a 2025 study of 1,904 soldiers. The 2023 study also found the tape method picked up only part of the change in body fat over 8 weeks of training (none of it in women), so it is a weak tool for tracking small changes. A result a few points either side of a band edge could belong to the neighboring band. To see where fat is stored, the waist-to-hip ratio calculator adds context, and BMI gives the overall picture.
Frequently asked questions
What is a healthy body fat percentage for women?
In Gallagher and colleagues' study, the healthy range for white women was about 21% to 33% at ages 20-39, 23% to 35% at 40-59 and 25% to 38% at 60-79. These are the body fat levels that matched a BMI of 18.5 to 25.
What is a healthy body fat percentage for men?
For white men the same study gives about 8% to 21% at ages 20-39, 11% to 23% at 40-59 and 13% to 25% at 60-79. Men carry less body fat than women at the same BMI.
How do I calculate my body fat percentage at home?
Measure your height, neck and waist (and hips if you are a woman) with a tape measure, then enter them above. The US Navy equations turn those measurements into an estimate. Smart scales use electrical impedance instead; both are estimates and can disagree.
How accurate is the US Navy body fat calculator?
In studies of US soldiers, it read lower than DXA scans on average, with typical individual errors of about 4 to 6 percentage points. Use it for a rough picture and for long-term trends measured the same way.
Is body fat percentage better than BMI?
It measures something BMI cannot: how much of your weight is fat. Two people with the same BMI can differ a lot in body fat, especially if one is very muscular. In practice the tape estimate has its own error, so the two numbers are best read together.
Sources
- Potter AW, Tharion WJ, Holden LD, et al. Circumference-based predictions of body fat revisited: preliminary results from a US Marine Corps body composition survey. Front Physiol. 2022;13:868627. (Prints the Hodgdon-Beckett US Navy equations.)
- Taylor KM, Castellani MP, Bartlett PM, et al. Development and cross-validation of a circumference-based predictive equation to estimate body fat in an active population. Obes Sci Pract. 2024;10(2):e747.
- McClung HL, Bartlett PM, Spiering BA, et al. Science behind policy: implementing a modern circumference-based body fat equation with a physical fitness threshold is associated with lower musculoskeletal injury risk. Int J Obes. 2025;49(4):723-730.
- Foulis SA, Friedl KE, Spiering BA, et al. Body composition changes during 8 weeks of military training are not accurately captured by circumference-based assessments. Front Physiol. 2023;14:1183836.
- Gallagher D, Heymsfield SB, Heo M, Jebb SA, Murgatroyd PR, Sakamoto Y. Healthy percentage body fat ranges: an approach for developing guidelines based on body mass index. Am J Clin Nutr. 2000;72(3):694-701.
- Colombo O, Villani S, Pinelli G, et al. To treat or not to treat: comparison of different criteria used to determine whether weight loss is to be recommended. Nutr J. 2008;7:5. (Table 1 reproduces the Gallagher cut-offs for white adults.)