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Body Fat Calculator: US Navy Method

This free body fat calculator uses the US Navy circumference method. With a tape measure you can estimate your body fat percentage, fat mass and lean mass without special equipment.

By Debmedia Technologies LLP · Kolkata, India · Updated

What Is It and When Do You Need It?

Body fat percentage shows how much of your weight is fat. It tells more than BMI about health and fitness, because it separates fat from muscle. The US Navy method gives a useful estimate with only a tape measure.

Enter your height and measurements, and optionally your weight, to see your body fat percentage and a split into fat mass and lean mass.

How to Use This Tool

  1. Choose sex and units.
  2. Enter your height, neck and waist, and hip for women.
  3. Optionally enter your weight.
  4. Press Calculate.

How the Calculation Works

Measurements are converted to centimetres. For men, body fat % = 495 ÷ (1.0324 − 0.19077 × log10(waist − neck) + 0.15456 × log10(height)) − 450. For women, body fat % = 495 ÷ (1.29579 − 0.35004 × log10(waist + hip − neck) + 0.22100 × log10(height)) − 450. Fat mass and lean mass follow from your weight.

Worked Example

A man 175 cm tall with a 38 cm neck and an 88 cm waist has about 19.2% body fat. At 75 kg, that is about 14.4 kg of fat and 60.6 kg of lean mass.

Common Uses

  • Tracking fat loss better than weight.
  • Training and diet plans.
  • Checking progress without a lab.
  • Health checks.

Tips and Common Mistakes

  • Measure at the same time of day each time.
  • Small measurement errors change the result a few points.
  • Use the trend, not a single reading.

Next, you may need the BMI calculator, ideal weight calculator, BMR and TDEE calculator, calorie deficit calculator.

Everything runs in your browser. Nothing you type is uploaded, stored or sent to any outside service.

Frequently Asked Questions

It uses the difference between waist and neck size (and hip size for women) with height, in a formula fitted to body density measurements.
It is usually within three to four percentage points for most people. DEXA scans and water weighing are more accurate.
For men, about 10 to 20 percent is typical for fitness and health, and for women about 18 to 28 percent. Needs vary with age and goals.
Stand relaxed, breathe out normally, keep the tape snug but not tight and level with the floor, and measure twice.

Disclaimer: results are calculated in your browser from the numbers you enter. Check important results before you rely on them for money, health, safety or legal decisions.