Body Fat Calculator

What is a Body Fat Calculator?

A body fat calculator estimates the percentage of your total body weight that is fat tissue, using the US Navy circumference method. It is more informative than BMI because it measures body composition directly rather than inferring it from height and weight alone.

How It Works

The US Navy method uses body circumference measurements:

Men:   495 / (1.0324 - 0.19077 x log(waist - neck) + 0.15456 x log(height)) - 450
Women: 495 / (1.29579 - 0.35004 x log(waist + hip - neck) + 0.22100 x log(height)) - 450

Example

A man with 178 cm height, 90 cm waist, 38 cm neck.

  • Result: approximately 20-22% body fat — Average category

Tips

  • Measure at the same time of day, ideally in the morning before eating. Measurements fluctuate throughout the day.
  • For the waist, measure at the narrowest point (typically at or just above the navel for men, at the natural waist for women).
  • Measure the neck just below the larynx. Pull the tape snug but not tight.

Frequently Asked Questions

What is a healthy body fat percentage?

For men, 6-17% is considered athletic to fit, 18-24% is average. For women, 14-24% is athletic to fit, 25-31% is average. Essential fat (needed for basic biological function) is around 3-5% for men and 10-13% for women.

How accurate is the Navy method?

The Navy method has an error margin of around 3-4% compared to more clinical methods like DEXA scans. It is best used for tracking changes over time rather than determining an exact number.

What is the difference between body fat percentage and BMI?

BMI is calculated from height and weight and cannot distinguish muscle from fat. Body fat percentage directly measures the fat-to-lean ratio, making it more useful for athletes or anyone who carries significant muscle mass.

How can I lower my body fat percentage?

A combination of a moderate calorie deficit and resistance training is the most effective approach. Resistance training preserves and builds muscle while the deficit drives fat loss. Cardio supports overall health and can increase the deficit, but muscle retention comes from training.