Calculators
Navy Body Fat Calculator
Estimate body fat with the US Navy circumference equations, or the Army’s 2023 one-site tape, and see the exact formula applied to your numbers.
Body fat % = 86.010 × log10(abdomen − neck) − 70.041 × log10(height) + 36.76, all in inches. Centimetre inputs are divided by 2.54 first.
| Category | Men | Women |
|---|---|---|
| Essential fat | 2–5% | 10–13% |
| Athletes | 6–13% | 14–20% |
| Fitness | 14–17% | 21–24% |
| Average | 18–24% | 25–31% |
| Obese | 25% and over | 32% and over |
Sources and current status
US Navy equations: Hodgdon and Beckett, Naval Health Research Center, 1984 (men, women), in the inch form published in DoD Instruction 1308.3 (2002). These coefficients reproduce every cell of the Navy’s own percent body fat charts (Navy PRP Guide 4) when rounded to whole percent. The Navy replaced this neck-based method with a waist-to-height screen in OPNAVINST 6110.1L (December 2025).
Army one-site equations and Table B-2: ALARACT 046/2023 implementing Army Directive 2023-11, whose worked examples (210 lb, 35 in man: 17.48%; 165 lb, 30 in woman: 26.475%) this tool reproduces. Replaced in July 2026, per army.mil.
Categories: American Council on Exercise general reference ranges, not a medical diagnosis.
Tape estimates are for adults and are not a scan or an official military assessment. Measurements stay in your browser.
Works in your browser. No account needed.
Frequently asked questions
What is the US Navy body fat formula?
For men: body fat % = 86.010 × log10(abdomen − neck) − 70.041 × log10(height) + 36.76. For women: 163.205 × log10(waist + hip − neck) − 97.684 × log10(height) − 78.387. All measurements are in inches. These are Hodgdon and Beckett’s 1984 Naval Health Research Center equations in the form published in DoD Instruction 1308.3. Rounded to whole percent, they reproduce the Navy’s printed body fat charts.
Why does the metric version give the same answer as the imperial one?
Because this tool converts centimetres to inches (÷ 2.54) and kilograms to pounds before using the equations. Many sites use a separate centimetre formula (495 ÷ body density − 450). That version can differ from the Navy charts by up to about one percentage point, so it is not used here.
How did the Army one-site tape test work?
From June 2023, the Army estimated body fat from abdominal circumference at the navel and body weight only. Men: −26.97 − 0.12 × weight (lb) + 1.99 × abdomen (in). Women: −9.15 − 0.015 × weight (lb) + 1.27 × abdomen (in). The published examples give 17.48% for a man at 210 lb with a 35-inch abdomen and 26.475% for a woman at 165 lb with a 30-inch abdomen. Both are rounded to whole percent: 17% and 26%.
Is this still the official Navy or Army test?
No. The Navy’s December 2025 instruction, OPNAVINST 6110.1L, replaced the neck-based tape method with a waist-to-height ratio screen. Army Directive 2026-13 (July 2026) rescinded the Army tape test and its body fat limits. The Army now requires a waist-to-height ratio under 0.55. Use this tool to understand the equations or track your own changes over time, not to predict an official result.
What do the half-inch rounding and the category mean?
The Navy guide rounds neck measurements up and waist, abdomen and hip measurements down to the nearest half inch. Height is rounded up, and the Army rounds weight to the nearest pound. The second number applies those rules and rounds to whole percent. The category comes from the American Council on Exercise ranges, for example 18–24% average for men and 25–31% for women. It is a general reference, not a diagnosis.
About this tool
The Navy tape method estimates body fat from circumferences. Men are measured at the neck, just below the larynx, and at the abdomen across the navel. Women are measured at the neck, the natural waist (the narrowest point) and the widest part of the hips. Height is part of both equations. Because the equations use the logarithm of abdomen or waist plus hip minus neck, a larger neck lowers the estimate and a larger midsection raises it.
The Army’s 2023 one-site method left out the neck and height and used a linear equation in abdominal girth and weight. Because weight has a negative coefficient, two people with the same abdomen get a lower estimate for the heavier one. The Army mode also shows the AR 600-9 Table B-2 limits that applied under this method, from 20% (men aged 17–20) to 36% (women aged 40 and older). That table is no longer in force.
Tape estimates depend on where the tape sits and how tight it is. Take each measurement at least twice, horizontal, on bare skin (hips over thin shorts), snug but not compressing, after a normal breath out. Use the average. For the male Navy mode, the tool also shows abdomen ÷ height, the waist-to-height ratio the services now use.
If you enter weight, the tool splits it into fat mass (weight × estimated percentage) and fat-free mass (the rest). Those figures carry the same uncertainty as the percentage. Results outside 2–60% are withheld as a likely unit or measurement error. Nothing you enter leaves your browser.