CalcPenguin

Body Fat Calculator

Estimate your body fat percentage with a tape measure using the US Navy method, and see your fat mass and lean mass.

Your numbers are saved in this browser.
cm
kg
cm
cm

Body fat

19.2% average

Fat mass
15 kg
Lean mass
63 kg

About 19.2% of your weight is fat (15 kg), in the "average" range for men.

How it's worked out

  1. Waist minus neck88 − 3850 cm
  2. US Navy formula495 ÷ (1.0324 − 0.19077 × log(waist − neck) + 0.15456 × log(height)) − 45019.2%
  3. Fat mass78 kg × 19.2%15 kg
  • A tape-measure estimate, usually within 3 to 4 percentage points of a lab scan. Measure in the morning, tape level and snug.

The US Navy formula (metric)

Men: 495 ÷ (1.0324 − 0.19077 × log(waist − neck) + 0.15456 × log(height)) − 450

Worked example

A man 175 cm tall with an 88 cm waist and 38 cm neck: log(50) = 1.699 and log(175) = 2.243, giving 495 ÷ 1.0550 − 450 = 19.2% body fat, in the "average" range.

Questions people ask

How accurate is the US Navy method?

It usually lands within 3 to 4 percentage points of a lab scan, good enough to track changes over time with the same tape and technique.

Where do I measure?

Waist at the navel, neck just below the Adam's apple, and for women the hips at their widest. Keep the tape level and snug, not tight.

What is a healthy body fat?

On the American Council on Exercise scale, about 14% to 24% for men and 21% to 31% for women covers the fitness to average ranges.

Formula and rules last checked 25 October 2026Written and tested by the CalcPenguin teamReport a problem