Body Fat Calculator
Estimate your body fat percentage with a tape measure using the US Navy method, and see your fat mass, lean mass and fitness category.
Categories from the American Council on Exercise. The tape method is usually within 3 to 4 percentage points of lab tests.
How to measure
Use a soft tape measure on bare skin. Keep it level and snug without pressing in, and take each measurement twice.
- Neck: just below the Adam’s apple, with the tape sloping slightly down at the front.
- Waist (men): around the navel, after breathing out normally.
- Waist (women): at the narrowest point, usually just above the navel.
- Hips (women): around the widest part of the buttocks.
- Height: standing straight without shoes.
The US Navy formula
This method was developed by the US Naval Health Research Center and uses the relationship between body circumferences and height. With measurements in inches:
- Men: 86.010 × log10(waist − neck) − 70.041 × log10(height) + 36.76
- Women: 163.205 × log10(waist + hip − neck) − 97.684 × log10(height) − 78.387
Body fat categories
The American Council on Exercise uses these ranges:
- Men: essential fat 2–5%, athletes 6–13%, fitness 14–17%, average 18–24%, obese 25% or more.
- Women: essential fat 10–13%, athletes 14–20%, fitness 21–24%, average 25–31%, obese 32% or more.
How accurate is it?
For most adults, the tape method is within about 3 to 4 percentage points of laboratory methods such as DEXA scans. It is less accurate for very muscular people and for people with a lot of fat around the hips or thighs. The best use is to track changes over time: measure the same way, at the same time of day, every few weeks.
This tool is for general information and is not medical advice.
Body Fat Calculator FAQs
Answers about measuring, accuracy and healthy ranges.
What is a healthy body fat percentage?+
For men, around 14% to 24% is in the fitness to average range. For women, around 21% to 31%. Very low levels can be as unhealthy as very high ones.
Is the US Navy method accurate?+
It is usually within 3 to 4 percentage points of lab tests for most adults, which makes it a good, free way to track progress over time.
Why do women need a hip measurement?+
Women tend to store more fat around the hips and thighs, so the formula for women adds the hip measurement for a better estimate.
How is body fat different from BMI?+
BMI only uses height and weight, so it cannot tell muscle from fat. Body fat percentage estimates how much of your weight is fat.
Is my data saved?+
No. Everything is calculated in your browser, and your measurements are never sent to our servers.
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