Body Fat Calculator
Estimate your body fat percentage with the US Navy tape-measure method or from your BMI and age, and see where you fall on the ACE body fat chart along with your fat and lean mass.
Measure the neck just below the larynx and the waist horizontally at the navel, relaxed, without pulling the tape tight.
Body fat categories (ACE)
| Category | Men | Women |
|---|---|---|
| Essential fat | 2–5% | 10–13% |
| Athletes | 6–13% | 14–20% |
| Fitness | 14–17% | 21–24% |
| Average | 18–24% | 25–31% |
| Obese | 25%+ | 32%+ |
How to use the Body Fat Calculator
- Choose a method: US Navy if you have a tape measure, or BMI if you only know your weight and height.
- Pick your sex and units, metric or imperial.
- Enter your measurements: height, neck and waist (and hips for women), or weight and age for the BMI method.
- Press Calculate to see your body fat percentage and ACE category.
- Add your weight to see your fat mass and lean mass.
The US Navy body fat formula
The US Navy method estimates body fat from circumference measurements and height, all in inches:
- Men: body fat % = 86.010 × log10(waist − neck) − 70.041 × log10(height) + 36.76
- Women: body fat % = 163.205 × log10(waist + hip − neck) − 97.684 × log10(height) − 78.387
Example: a man 70 in tall (5 ft 10 in) with a 15 in neck and a 34 in waist. Waist − neck = 19, and log10(19) = 1.2788, so the first term is 86.010 × 1.2788 = 109.99. log10(70) = 1.8451, so the second term is 70.041 × 1.8451 = 129.23. Body fat = 109.99 − 129.23 + 36.76 ≈ 17.5%, which is in the Fitness range. At 176 lb that is about 30.8 lb of fat mass and 145.2 lb of lean mass.
The BMI (Deurenberg) formula
When you only know weight, height and age, body fat can be estimated from BMI: body fat % = 1.20 × BMI + 0.23 × age − 10.8 × sex − 5.4, where sex is 1 for men and 0 for women. BMI = weight (kg) ÷ height (m)².
Example: a 35-year-old woman, 165 cm and 65 kg. BMI = 65 ÷ 1.65² = 23.9. Body fat = 1.20 × 23.9 + 0.23 × 35 − 0 − 5.4 = 28.65 + 8.05 − 5.4 ≈ 31.3%, in the Average range.
Body fat percentage chart by age
Healthy ranges rise slightly with age. These commonly cited ranges come from Gallagher et al. (2000):
| Age | Men: healthy | Men: overfat | Women: healthy | Women: overfat |
|---|---|---|---|---|
| 20–39 | 8–19% | 20–24% | 21–32% | 33–38% |
| 40–59 | 11–21% | 22–27% | 23–33% | 34–39% |
| 60–79 | 13–24% | 25–29% | 24–35% | 36–41% |
Body fat estimates are for general guidance only and are not a medical diagnosis.
Frequently asked questions
How accurate is the US Navy body fat method?
For most people the Navy tape method lands within about 3 to 4 percentage points of a DEXA scan or hydrostatic weighing. Accuracy depends on careful, consistent measurements, so measure two or three times and use the average.
Where do I measure my neck, waist and hips?
Measure the neck just below the Adam's apple, sloping slightly down at the front. Men measure the waist horizontally at the navel; women at the narrowest point. Hips are measured at the widest part of the buttocks. Keep the tape snug but not tight and do not suck in.
What is a healthy body fat percentage?
According to the American Council on Exercise, about 14 to 24% is fit to average for men and 21 to 31% for women. Essential fat, the minimum needed for health, is about 2 to 5% for men and 10 to 13% for women.
Why is the BMI method less accurate?
BMI only uses weight and height, so it cannot tell muscle from fat. Muscular people tend to get an overestimate and people with little muscle an underestimate. Use the Navy method when you can.
What is lean body mass?
Lean body mass is everything that is not fat: muscle, bone, organs and water. It is your weight minus your fat mass, where fat mass is weight × body fat percentage.
Why do women have a higher body fat percentage?
Women naturally carry more essential fat, which supports hormonal and reproductive health. That is why the healthy ranges and the formulas are different for men and women.