Body Fat Calculator
Estimate your body fat percentage from a tape measure: waist, neck and hips. Uses the US Navy method, with fat and lean mass and your ACE category. Free.
Measure the waist at the navel (men) or the narrowest point (women), the neck just below the larynx, and the hips at the widest point.
- Fat mass
- 12.7 kg
- Lean mass
- 62.3 kg
An estimate from a published formula, for general information. It isn't medical advice; talk to a doctor or dietitian about your own needs.
Body fat from a tape measure
The US Navy method estimates body fat from your height and a few circumferences: the waist and neck for men, plus the hips for women. Studies put it within about 3–4 percentage points of lab methods such as DEXA for most people, which is close enough to track progress at home. The result is grouped into the American Council on Exercise categories: essential fat, athletes, fitness, average and obese. Add your weight to see how much of it is fat and how much is lean mass (muscle, bone, organs and water).
How to use it
- 1
Measure yourself
Use a soft tape, relaxed, without pulling it tight. Measure twice and use the average.
- 2
Enter the numbers
Sex, height and weight, plus your waist and neck (and hips for women).
- 3
Read your body fat
Re-measure every few weeks at the same time of day to track changes.
Frequently asked questions
What is a healthy body fat percentage?
For men, about 14–24% is fitness to average; for women, 21–31%. Athletes are often lower, and below 6% for men or 14% for women is essential fat only.
How accurate is the Navy method?
Typically within 3–4 percentage points of DEXA scans. It's less accurate for very lean or very muscular people, and consistent measuring matters more than the exact number.
Where do I measure my waist?
Men: horizontally at the navel. Women: at the narrowest point, usually just above the navel. Breathe out normally before measuring.
Is anything sent to a server?
No. Everything is calculated in your browser, and nothing you type is stored or sent anywhere.