Body Fat Calculator
This calculator estimates body fat percentage using the US Navy circumference method, which needs nothing more than a tape measure. Men measure neck and waist; women add the hip measurement. The formula was developed for military fitness assessments and correlates reasonably well with more expensive methods for most body types.
- Estimated body fat
- 18.4%
- Category (ACE)
- Average
Body fat percentage tells you something BMI cannot: how much of your weight is fat versus everything else (muscle, bone, water, organs). Two people with identical BMI can have very different body compositions, which is why athletes often prefer this measure.
How it's calculated
Men: %fat = 495 / (1.0324 − 0.19077·log₁₀(waist − neck) + 0.15456·log₁₀(height)) − 450
Women use 495 / (1.29579 − 0.35004·log₁₀(waist + hip − neck) + 0.221·log₁₀(height)) − 450, with all measurements in centimeters. Measure the waist at the navel for men and at the narrowest point for women, the neck just below the larynx, and the hips at their widest point.
Worked example
A man 180 cm tall with a 38 cm neck and 88 cm waist: log₁₀(88 − 38) = 1.699, log₁₀(180) = 2.255, giving 495 / (1.0324 − 0.3241 + 0.3486) − 450 ≈ 18.4% body fat, which falls in the average range for men.
Frequently asked questions
›How accurate is the tape measure method?
Studies put the Navy method within about 3 to 4 percentage points of underwater weighing for most people. It is less accurate for very muscular or very lean individuals. Measuring at the same time of day with a relaxed posture improves consistency.
›What is a healthy body fat percentage?
The American Council on Exercise categorizes men as: athletes 6 to 13%, fitness 14 to 17%, average 18 to 24%, above average 25%+. For women: athletes 14 to 20%, fitness 21 to 24%, average 25 to 31%, above average 32%+. Women naturally carry more essential fat than men.
›Why do women have a higher healthy range?
Essential fat, the minimum needed for hormones and organ function, is about 3% for men but 12% for women because of reproductive physiology. The ranges shift up accordingly.
›Can I lose fat in one specific spot?
No. Spot reduction has been repeatedly debunked; fat loss happens across the whole body, in an order set mostly by genetics. Overall calorie balance and training drive the result.
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