Body Fat Percentage Calculator

Estimate your body fat percentage using the US Navy method with neck, waist, and hip circumference measurements.

Body Fat Percentage Calculator tool

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Example

Input: Male, height 178 cm, waist 86 cm, neck 38 cm, weight 80 kg

Result: Body Fat Percentage 17.2 % (Fitness), Fat Mass 13.8 kg, Lean Body Mass 66.2 kg

US Navy formula: 495 / (1.0324 - 0.19077 x log10(86 - 38) + 0.15456 x log10(178)) - 450 = 17.2%, and 80 x 17.2% = 13.8 kg of fat.

Body Fat Categories Used by This Calculator

CategoryMenWomen
Essential fatUnder 6%Under 14%
Athletes6% to 13.9%14% to 20.9%
Fitness14% to 17.9%21% to 24.9%
Average18% to 24.9%25% to 31.9%
Obese25% and above32% and above

Bands follow the widely used American Council on Exercise (ACE) chart.

  1. Select your sex (male or female) to use the correct formula.
  2. Enter your height in centimeters and your body weight in kilograms.
  3. Measure and enter your neck circumference in centimeters just below the larynx.
  4. Measure and enter your waist circumference at the navel.
  5. For women, measure and enter your hip circumference at the widest point.
  6. View your estimated body fat percentage, lean mass, and body fat category.

Estimating Body Fat With a Tape Measure

Body fat percentage is the share of your weight that is fat. This calculator estimates it with the US Navy method, which needs only a tape measure. For a man who is 178 cm tall with an 86 cm waist and a 38 cm neck, the estimate is 17.2%. At 80 kg, that is about 13.8 kg of fat.

The method uses a formula based on body measurements. Men enter height, neck and waist. Women also enter hips, because women tend to store more fat there. Add your weight and the tool also shows fat mass and lean body mass, which is everything that is not fat: muscle, bone, organs and water. It places the result in one of five categories, listed in the table below.

Good measuring makes a big difference, since a small tape error can shift the result by a point or more. Use a flexible tape, keep it level and snug without squeezing, and do not pull in your stomach. Measure the neck just below the Adam's apple. Men measure the waist at the navel, and women at the narrowest point. Women measure the hips at the widest part of the buttocks. Take each reading twice and use the average.

The Navy method is an estimate. Compared with lab methods such as DEXA scans, it can be off by several percentage points for one person. It works best for tracking change over time, measured the same way each time. Body fat tells you more than weight alone, but it is still one number. For a quick height-and-weight screen, see the BMI Calculator. A doctor can put your results in context with other health checks.

Formula / How It Works

Men: %BF = 495 / (1.0324 - 0.19077 x log10(waist - neck) + 0.15456 x log10(height)) - 450. Women: %BF = 495 / (1.29579 - 0.35004 x log10(waist + hip - neck) + 0.22100 x log10(height)) - 450. All measurements in cm.

Frequently Asked Questions

It uses the logarithm of body measurements to estimate body fat. For men, the inputs are waist minus neck, plus height. For women, it is waist plus hips minus neck, plus height. The formula was built by comparing tape measurements with more precise lab tests.
This tool uses a widely used fitness chart. For men, 14% to 17.9% is the fitness range and 18% to 24.9% is average. For women, 21% to 24.9% is fitness and 25% to 31.9% is average. Healthy ranges also shift with age, so ask a doctor what fits you.
Measure the neck just below the Adam's apple, with the tape sloping slightly down at the front. Men measure the waist at the navel. Women measure the waist at its narrowest point and the hips at the widest part of the buttocks. Stand relaxed and do not hold your breath.
It gives a reasonable estimate for many people, but it can miss by several percentage points compared with DEXA or underwater weighing. Accuracy depends a lot on careful measuring. It is most useful for tracking trends when you measure the same way each time.
Every two to four weeks is plenty, because body composition changes slowly. Measure at the same time of day, ideally in the morning before eating. Day-to-day changes are mostly measuring noise and water, so look at the trend over several readings.

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