Download
Calculator

Body Fat Calculator

All you need is a tape measure and two minutes. The calculator estimates your body fat percentage from your measurements and shows how your waist size compares.

Sex

Measure with a tape measure while standing, after breathing out gently. Neck: just below the larynx. Waist: women at the narrowest point, men at the level of the navel. Hips: around the widest part of your buttocks.

Enter your details and your results will appear here.

How does the US Navy method work?

The calculator uses a formula developed for the US Navy (Hodgdon and Beckett, 1984). It estimates body density from your neck and waist measurements (and hip measurements for women), along with your height, then uses that to estimate your body fat percentage.

Formulas for measurements in centimeters:

  • men: 495 ÷ (1.0324 - 0.19077 × log(waist - neck) + 0.15456 × log(height)) - 450,
  • women: 495 ÷ (1.29579 - 0.35004 × log(waist + hips - neck) + 0.221 × log(height)) - 450.

Example: a man who is 180 cm tall, with a neck circumference of 38 cm and a waist circumference of 85 cm, has an estimated body fat percentage of about 16%. The same person with a waist circumference of 95 cm would have about 23%.

How to measure yourself

You’ll need a tape measure and a mirror, or someone to help you. Measure while standing, in the morning before eating:

  1. Neck - just below the larynx (Adam’s apple), with the tape sloping slightly downward at the front.
  2. Waist - women at the narrowest point, usually above the navel; men at the level of the navel. Breathe out gently and don’t suck in your stomach.
  3. Hips (women only) - around the widest part of your buttocks.

Measure each circumference twice and enter the average. Keep the tape measure horizontal and against your skin without pulling it tight.

Body fat ranges

Categories according to the American Council on Exercise:

Category Women Men
Bare minimum 10-13% 2-5%
Athletes 14-20% 6-13%
Fitness 21-24% 14-17%
Average 25-31% 18-24%
Too much body fat 32% and above 25% and above

Women naturally have more body fat than men. It’s needed, among other things, for normal hormone function. Falling below the essential minimum is not healthy.

Waist-to-height ratio

The calculator also shows your waist-to-height ratio. This is a simple indicator of the amount of fat around your abdomen:

  • below 0.5 - within the healthy range,
  • 0.5-0.59 - increased risk,
  • 0.6 and above - high risk.

Fat stored around the internal organs is linked to a higher risk of conditions including type 2 diabetes and heart disease. That’s why waist circumference can tell you more about your health than weight alone or BMI. If your result is high, consider discussing it with a doctor. For practical tips, read the article How to Lose Belly Fat.

FAQs

What body fat percentage is considered healthy?
According to the American Council on Exercise, typical body fat ranges are 25-31% for women, while 21-24% indicates fitness. For men, the respective ranges are 18-24% and 14-17%. Body fat is considered too high from around 32% for women and 25% for men.
How accurate is the circumference method?
The US Navy method is usually off by 3-4 percentage points compared with laboratory tests. It works well for tracking changes over time, as long as you measure yourself the same way each time.
How do you measure your waist circumference?
Stand up straight, relax your stomach, and breathe out gently. Women should measure their waist at its narrowest point, and men at the level of the navel. Keep the tape measure horizontal and against your skin without pulling it tight.
Is a body fat scale more accurate?
Bathroom scales that measure body composition also only provide estimates. Results can vary by several percentage points depending on hydration, time of day, and meals. For the best comparison, take measurements under the same conditions, such as first thing in the morning before eating.
What is a healthy waist circumference?
According to WHO, the risk of obesity-related diseases increases from 80 cm for women and 94 cm for men, and rises significantly from 88 and 102 cm, respectively. A simple rule of thumb: your waist circumference should be less than half your height.
How can you reduce body fat?
You need a moderate calorie deficit, enough protein, and strength training to help preserve muscle. Unfortunately, you can’t burn fat from just one chosen area, such as your stomach.

This calculator is for informational purposes only and does not replace advice from a doctor or dietitian. The calculations happen in your browser—we don’t send the data you enter anywhere. We only save it in this tab for the duration of your visit, so it can be filled in automatically in other calculators. Formulas and sources.

Other calculators