Calcs4All

APR 23 · 2026

Body fat calculator

Estimate body fat percentage from circumference measurements.

What this calculator covers

Use this body fat calculator to estimate body-fat percentage from tape measurements instead of relying on scale weight alone.

The calculator uses the U.S. Navy circumference method and shows the measurement term that feeds the formula, which makes it easier to spot unrealistic inputs.

Small tape-measure differences can move the result noticeably, so repeat measurements taken at consistent landmarks usually matter more than extra decimal places.

Frequently asked questions

Where exactly is the waist measured for this method?
For the Navy circumference method, the male waist is measured at the navel. The female waist is measured at the narrowest point of the torso. Taking the tape at the wrong location can shift the result by several percentage points.
Why is the hip measurement only needed for females?
The Navy formula for females uses waist plus hips minus neck as the circumference term because it was developed to account for sex-specific fat distribution patterns. The male formula uses only waist minus neck.
How does this compare to a DEXA scan?
The circumference method is a field estimate — practical and equipment-free, but less precise than laboratory techniques such as DEXA or hydrostatic weighing. It can be several percentage points off from a gold-standard measurement.
Can I use metric measurements?
Yes. Switch the unit system to metric and enter height in centimeters and circumferences in centimeters. The calculator converts to inches internally before applying the published Navy constants.

Tool

Run the calculation

RESULT · BODY FAT

â„–102

Primary result

28.6%

Using the U.S. Navy circumference method, the estimated body fat level is 28.6% for the selected female measurements.

Height used
65 in
Measurement term
55 in
Method
U.S. Navy (female)
Estimated body fat
28.6%

Step-by-step solution

  1. 1.Convert the selected measurements to inches internally: height 65, neck 13, waist 30, and hip 38.
  2. 2.Build the Navy-method measurement term: 30 + 38 - 13 = 55.
  3. 3.Apply the female Navy formula and round to one decimal place for an estimate of 28.6%.

Walkthrough

Visual walkthrough

The Navy method uses circumference measurements rather than scale weight to estimate body-fat percentage.

  1. 01

    Convert measurements into inches

    1 in = 2.54 cm

    The published Navy constants are inch-based, so metric inputs are converted before the logarithms are taken.

  2. 02

    Build the circumference term

    30 + 38 - 13 = 55

    Men use waist minus neck. Women use waist plus hip minus neck.

  3. 03

    Read the estimated percentage

    The log-based Navy equation compares the measurement term with height to produce a body-fat estimate.

    28.6%