Body Fat Percentage Calculator (U.S. Navy Method)
Measure your waist, neck (and hips for women) with a tape and get a body fat estimate — no scale, no calipers.
How it’s calculated
This uses the Deurenberg equation, which estimates body fat from BMI, age, and sex — no calipers needed.
Body fat % = 1.20 × BMI + 0.23 × age − 10.8 × sex − 5.4 (men sex = 1, women sex = 0).
Source: Deurenberg P, et al., British Journal of Nutrition, 1991.
Body fat percentage chart: women and men
| Category (ACE) | Women | Men |
|---|---|---|
| essential fat | 10 – 13% | 2 – 5% |
| athletes | 14 – 20% | 6 – 13% |
| fitness | 21 – 24% | 14 – 17% |
| average | 25 – 31% | 18 – 24% |
| above average | 32%+ | 25%+ |
Women need more essential fat for hormones and reproduction, which is why every band is higher. Body fat also tends to rise gradually with age at the same weight.
How to measure body fat at home
Use a soft tape, measure in the morning, tape snug but not tight. Waist: at the navel (men) or narrowest point (women). Neck: just below the larynx, tape sloping slightly down at the front. Hips (women): widest point. Enter the numbers with your height; the calculator applies the U.S. Navy circumference equations.
Navy vs Army method
Both use tape measurements. The Navy formula uses neck, waist and (for women) hips; the Army standard measures waist only, at the navel, and reads it against height and sex. The Navy method is the one used here because it is the better-validated of the two for the general public. Expect an error of about ±3–4 percentage points versus a DEXA scan.
What is a healthy body fat percentage?
For general health most adults do well in the “fitness” to “average” bands above. Very low body fat is not a health goal: below essential levels hormones, bone and immunity suffer. Rather than chasing a single number, watch the trend every 4–6 weeks under the same conditions.
Sources
- Hodgdon JA, Beckett MB. Prediction of percent body fat for U.S. Navy men and women from body circumferences and height. Naval Health Research Center, 1984
- American Council on Exercise (ACE), body fat percentage categories — https://www.acefitness.org/resources/everyone/tools-calculators/percent-body-fat-calculator/
- WHO, Obesity and overweight — https://www.who.int/news-room/fact-sheets/detail/obesity-and-overweight
This calculator is educational and not medical advice. If you have a health condition, are pregnant, or are under 18, ask a clinician before changing your diet.
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