Body Fat Calculator
Estimate your body fat percentage from simple measurements.
Enter your measurements to see your body fat
The proportion of your body weight that's fat tissue. A more direct body composition measure than BMI.
How to use this calculator
- 1
Pick a method
US Navy uses a tape measure (neck and waist, plus hip for women) and performs better in published validation. Deurenberg uses just weight / height / age / sex — quicker but rougher.
- 2
Enter your stats
Sex, weight, and height are always needed. The US Navy method adds neck and waist (and hip for women); Deurenberg adds age.
- 3
Read your results
Your body fat %, the ACSM/ACE classification band, and a fat-vs-lean mass breakdown for your weight.
What is body fat percentage?
Body fat percentage is the proportion of your total weight that's fat mass, versus everything else (muscle, bone, organs, water: the "lean" mass). It's a more meaningful measure of body composition than weight or BMI alone.
Two people who weigh the same can have very different body fat percentages, and very different health profiles. This is why athletes routinely score "Overweight" on BMI but have low body fat.
What's "normal"?
Body fat ranges per ACSM / ACE. Note that "Essential fat" is the minimum needed for survival, not a target. The labels below are standard clinical and fitness-industry category names, not value judgments:
| Category | Men | Women |
|---|---|---|
| Essential | 2–5% | 10–13% |
| Athletes | 6–13% | 14–20% |
| Fitness | 14–17% | 21–24% |
| Average | 18–24% | 25–31% |
| Obese | 25%+ | 32%+ |
How is body fat calculated?
Two methods are supported. Both are estimates. For measured body composition you need DXA (dual-energy X-ray absorptiometry), hydrostatic weighing, or air-displacement plethysmography.
US Navy circumference method
Uses height plus tape measurements at the neck, waist (and hip, for women). Validated against hydrostatic weighing with ±3–4% typical error in published studies. Still an estimate rather than a measurement, but in that published validation it's generally the strongest tape-measure option you can do at home.
Men: %BF = 86.010 × log₁₀(waist − neck) − 70.041 × log₁₀(height) + 36.76
Women: %BF = 163.205 × log₁₀(waist + hip − neck) − 97.684 × log₁₀(height) − 78.387
All measurements in inches.
Deurenberg BMI-based formula (1991)
Uses just weight, height, age, and sex. No tape measure needed. Quicker but less accurate (±5–6% typical error).
%BF = 1.20 × BMI + 0.23 × age − 10.8 × sex − 5.4
sex: male = 1, female = 0