Body Fat Calculator
Body-fat percentage by the U.S. Navy tape method, with fat and lean mass.
What it does
Estimates body-fat percentage from tape measurements using the U.S. Navy method, and splits your weight into fat and lean mass.
Where it's used
Tracking body composition when you have no scanner — only a tape measure.
How to use it
- Choose sex and enter weight and height.
- Measure your neck just below the larynx.
- Measure your waist at the navel (and hips at their widest for women).
The formula explained
- Body fat %
- from logarithms of waist − neck (plus hip for women) and of height
- Fat mass
- weight × body fat %
- Lean mass
- weight − fat mass
Worked example
Inputs:
- Sex: Female
- Weight: 60 kg
- Height: 165 cm
- Neck circumference: 32 cm
- Waist (at navel): 72 cm
- Hip circumference: 96 cm
The calculator gives:
- Body fat: 26.4 %
- Category (ACE): Average
- Fat mass: 15.8 kg
Tips and common mistakes
- Measure relaxed, at the same time of day, with the tape level.
- Typical accuracy is about ±3–4 % compared with a DEXA scan.
- Track the trend over weeks rather than a single reading.
Questions people ask
What is the U.S. Navy formula?
It uses the logarithms of your measurements in cm. Women: 495 / (1.29579 − 0.35004 × log10(waist + hip − neck) + 0.22100 × log10(height)) − 450. Men: 495 / (1.0324 − 0.19077 × log10(waist − neck) + 0.15456 × log10(height)) − 450.
What body-fat percentage is typical?
By the American Council on Exercise categories, “average” is about 25–31 % for women and 18–24 % for men; “fitness” is 21–24 % and 14–17 %. Athletes are lower still.
Why measure body fat instead of BMI?
BMI uses only weight and height, so it can’t tell muscle from fat. Body fat splits your weight in two — in the example, 60 kg is about 15.8 kg of fat and 44.2 kg of lean mass.
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Enter your values to get the result with the formula, substituted values and an explanation of each step.