About the Army Body Fat Calculator
The US Army and Navy use a tape-measure method to estimate body fat without any special equipment. For men it uses height, neck and waist. For women it adds the hips. A formula based on the logarithms of those lengths converts them into a body fat percentage. This calculator applies the standard formulas, takes centimetres or inches, and gives your estimate with the general fitness category, from essential fat to above average. If you enter your body weight, it also splits it into fat mass and lean mass. It is a quick home estimate, usually within a few percentage points, and best used to track changes over time.
Updated October 2026
How to use the Army Body Fat Calculator
- 1Choose your sex and the unit of measurement.
- 2Enter your height, neck and waist. Women also enter hips.
- 3Optional: enter your body weight.
- 4Read the body fat percentage and the category.
- 5Repeat monthly with the same method to track progress.
Worked example
A man who is 178 cm tall with a 38 cm neck and 86 cm waist gets an estimate of about 17.3 percent body fat, in the fitness range. At 80 kg, that is about 13.8 kg of fat and 66.2 kg of lean mass. A woman who is 165 cm with a 33 cm neck, 75 cm waist and 98 cm hips gets about 28.7 percent, in the average range.
Tips for accurate measuring
- Measure first thing in the morning before eating.
- Keep the tape level and snug but not tight.
- Breathe out normally before measuring the waist.
- Use the same tape and the same places each time.
- Take the average of two or three measurements.
What to do with the number
Do not chase one reading. Track the trend over weeks, together with your waist measurement, strength and how clothes fit. A drop of 1 percentage point in a month is steady progress. If the figure seems far off from other measures, remember that the formula has built-in error, and look at the change rather than the exact value.
Related tools
The Body Fat Calculator offers other methods, the Lean Body Mass Calculator splits your weight, the BMI Calculator gives a height-to-weight ratio, and the Waist-to-Hip Ratio Calculator looks at fat distribution.
Features
- Army / Navy tape formula
- Centimetres or inches
- Fitness category
- Fat mass and lean mass from your weight
- Checks for unrealistic results
- Free and private
Frequently asked questions
How do I measure for the Army body fat formula?
Stand relaxed. Measure the neck just below the larynx, the waist at the navel for men or the narrowest point for women, and the hips at the widest point. Measure to the nearest half centimetre, twice, and use the average.
How accurate is the tape method?
Studies find it is typically within about 3 to 4 percentage points of more precise methods such as DEXA scans for most people. It is less reliable for very muscular, very lean or very overweight people.
What is a good body fat percentage?
For men, about 14 to 17 percent is considered fit and 18 to 24 percent average. For women, about 21 to 24 percent is fit and 25 to 31 percent average. Essential fat is about 2 to 5 percent for men and 10 to 13 percent for women.
Why does the formula need the neck measurement?
The neck is a proxy for lean tissue in the upper body. A larger neck with the same waist means less fat in proportion. The formula uses the difference between the waist (and hip) and the neck.
Is this the official Army test?
The formulas come from the Army and Navy method, but official standards change and are applied by trained staff using specific procedures. This tool is for personal estimates only.
What is lean body mass?
Everything in your body that isn't fat: muscle, bone, organs and water. It equals your weight minus fat mass. The Lean Body Mass Calculator on this site offers other formulas.