Skip to calculator
Calculate This

Body fat calculator

Measure your neck and waist (and hips for women) with a tape measure. You get your body fat percentage by the U.S. Navy method, your fat and lean mass, a BMI-based cross-check and where you sit on the ACE chart.

Defaults to your region. Switch to compare any other scale.

Sex

Result

17.4 %

Body fat (U.S. Navy method)

  • ACE categoryFitness
  • Fat mass30.7 lb
  • Lean body mass145.3 lb
  • Estimate from BMI (Deurenberg)22.2 %
  • BMI25.3

Fitness

Measure on bare skin in the morning, tape snug but not tight. The Navy method is usually within about 3–4 percentage points of lab tests. Not medical advice.

About this tool

How the U.S. Navy method works

The U.S. Navy formula (Hodgdon & Beckett, 1984) estimates body fat from height and circumferences. Men: BF% = 495 ÷ (1.0324 − 0.19077 × log10(waist − neck) + 0.15456 × log10(height)) − 450. Women add the hip: BF% = 495 ÷ (1.29579 − 0.35004 × log10(waist + hip − neck) + 0.22100 × log10(height)) − 450, all in centimetres.

Worked example

A man 178 cm tall with a 38 cm neck and 86 cm waist: waist − neck = 48 cm, so BF% = 495 ÷ (1.0324 − 0.19077 × 1.681 + 0.15456 × 2.250) − 450 ≈ 17.2%. At 80 kg that is about 13.8 kg of fat and 66.2 kg of lean mass.

ACE body fat chart

Men: essential fat 2–5%, athletes 6–13%, fitness 14–17%, average 18–24%, obese 25%+. Women: essential fat 10–13%, athletes 14–20%, fitness 21–24%, average 25–31%, obese 32%+.

BMI-based estimate

The Deurenberg equation (1.20 × BMI + 0.23 × age − 10.8 × sex − 5.4) needs no tape, but it cannot tell muscle from fat, so it overestimates for muscular people. Use it as a rough cross-check.

Accuracy

Tape methods are usually within about 3–4 percentage points of DEXA or hydrostatic weighing. Measure the same way each time to track change. This page is not medical advice.

Formula

  • Men: BF% = 495 ÷ (1.0324 − 0.19077 × log10(waist − neck) + 0.15456 × log10(height)) − 450
  • Women: BF% = 495 ÷ (1.29579 − 0.35004 × log10(waist + hip − neck) + 0.22100 × log10(height)) − 450
  • Measurements in cm (inches are converted × 2.54)
  • Fat mass = weight × BF% ÷ 100; lean mass = weight − fat mass
  • BMI method: BF% = 1.20 × BMI + 0.23 × age − 10.8 × (1 for men, 0 for women) − 5.4

How it is calculated

  1. Choose your sex and units.
  2. Measure your neck just below the larynx and your waist at the navel (women also measure the hips at the widest point).
  3. Enter height, weight and age.
  4. Read your body fat %, fat mass, lean mass and ACE category.

Questions

How do I calculate my body fat percentage?

With the U.S. Navy method you only need a tape measure: measure height, neck and waist (plus hips for women) and plug them into the formula. A 178 cm man with a 38 cm neck and 86 cm waist comes out at about 17%.

What is a healthy body fat percentage?

By the ACE chart, about 14–24% is fit to average for men and 21–31% for women. Below essential levels (about 2–5% men, 10–13% women) or in the obese range (25%+ men, 32%+ women) is worth discussing with a doctor.

How accurate is the U.S. Navy body fat formula?

Studies put it within roughly 3–4 percentage points of DEXA or underwater weighing for most adults. It is less reliable for very muscular or very lean people. Measure the same way each time and watch the trend.

Why is the BMI estimate different?

The Deurenberg BMI equation only uses weight, height, age and sex, so it cannot see whether weight is muscle or fat. Muscular people get too high a number. The tape-measure Navy result is usually the better one to follow.

Sources

Related calculators