Body Fat Calculator

Estimate your body fat

For adults (18+). Uses the U.S. Navy tape-measure method. Measure at the narrowest part of the neck, around the waist at the belly button (men) or narrowest point (women), and around the widest part of the hips (women).

How to Use

• Choose metric or US units, select your sex and enter your age (18+).
• Enter your weight, height, neck and waist. Women also enter hips.
• Use a soft tape measure, keep it level and snug but not tight, and measure twice.
• Click Calculate.

How accurate is it?

The U.S. Navy method is an estimate. Compared with a DXA body scan, a 2022 study found it read about 2–3 percentage points too low for men and about 1–2 points too high for women on average, and individual errors can be larger. The BMI-based estimate is even rougher and does not work well for very muscular people. Use the number to follow changes over time, not as an exact value.

Body fat includes essential fat (needed for life and hormones) and storage fat. The "essential fat" range is a minimum for health, not a goal: going below it is dangerous. If you are worried about your weight or eating, please talk to a doctor.

References

• American Council on Exercise (ACE) body fat categories

  Description	Women	Men
  Essential fat	10-13%	2-5%
  Athletes	14-20%	6-13%
  Fitness	21-24%	14-17%
  Average	25-31%	18-24%
  Obese	32%+	25%+

Formulas Used

• U.S. Navy Method (Metric):
  • Male: 495 / (1.0324 - 0.19077 × log₁₀(waist - neck) + 0.15456 × log₁₀(height)) - 450
  • Female: 495 / (1.29579 - 0.35004 × log₁₀(waist + hip - neck) + 0.22100 × log₁₀(height)) - 450
• BMI-based estimate (Deurenberg 1991, adults):
  • Male: 1.20 × BMI + 0.23 × Age - 16.2
  • Female: 1.20 × BMI + 0.23 × Age - 5.4

Sources

• American Council on Exercise – Percent body fat calculator and categories
• Potter AW et al. Circumference-based predictions of body fat revisited (reviews the Hodgdon & Beckett 1984 U.S. Navy equations against DXA). Front Physiol. 2022
• Deurenberg P et al. Body mass index as a measure of body fatness. Br J Nutr. 1991

Last reviewed 2026-09-26.