Calculate Your Body Fat

A simple, online body fat calculator.

Body Fat Calculator Explained

This body fat calculator was developed from a U.S. Department of Defense (DoD) instructional release. The underlying equations used in this calculator were developed by the U.S. Navy (see Notes) in 1984 and are currently utilized by the DoD.

The calculator uses circumference measurements of various locations on the body. For men, the circumference sites are the abdomen and the neck. For women, the circumference sites are the neck, waist, and hip.

The original equations require measurements in inches. However, we have added a conversion button for those who would prefer to perform the measurement in centimeters.

See below for instructions on how to perform each circumference site measurement.

What you will need to perform circumference measurements

  1. A tape measure, such as the one you can purchase at www.bodyfatcalipers.com
  2. Notepad and pen.
  3. A friend to help perform the measurements.

How to perform circumference measurements

For males:

Abdomen. First, your arms should be at your sides, in a relaxed position. Take the measuring tape and wrap it around your body at the naval (your belly button). The tape should rest against your skin but do not exert any additional pressure on the tape. As you exhale normally, take your measurement making sure that the measuring tape is parallel to the floor (so as to exact an accurate measurement). If you are using inches, then round down to the nearest ½ inch (39.75 inches becomes 39.5 inches, for example). Repeat a few times until you find you are taking consistent measurement.

Neck. Stand upright, shoulders relaxed (not hunched over) and eyes staring straight ahead. Now, find your larynx (Adam's Apple). At a point just below your larynx (not directly on the larynx) wrap the tape gently around your neck. The measuring tape should rest against your skin without any additional pressure being exerted. Take your measurement making sure the tape is in a horizontal position. If you are using inches, then round up to the nearest ½ inch (16.25 inches becomes 16.5 inches, for example. Repeat a few times until you find you are taking a consistent measurement.

For females:

Neck. Stand upright, shoulders relaxed (not hunched over) and eyes staring straight ahead. Now, find your larynx with your fingers. At a point just below your larynx (not directly on the larynx) wrap the tape gently around your neck. The measuring tape should rest against your skin without any additional pressure being exerted. Take your measurement making sure the tape is in a horizontal position. If you are using inches, then round up to the nearest ½ inch (16.25 inches becomes 16.5 inches, for example. Repeat a few times until you find you are taking a consistent measurement.

Waist. Stand upright, relax your arms to the side, and lift your clothing so that you can wrap the measuring tape directly against your skin. The natural waist is located at a point just above the naval (belly button) and below the rib cage. Wrap the tape around your waist making sure that it touches the skin but do not exert any additional pressure. If you are still unsure if you have found the right location to take your measurement, then perform the measurement a few times in probable locations. Make sure to take the measurement as you exhale regularly (do not force your breathing or try to empty or lungs of air). If you are measuring in inches then round your measurement down to the nearest ½ inch (27.25 inches becomes 27 inches, for example). Repeat a few times until you find you are taking a consistent measurement.

Hip. Have a person aid you in this measurement, if possible. Your partner will stand to the right side of you and will wrap the measuring tape around your hips so that it passes over the greatest portion of your buttocks (your "bum") when viewed from the side. Make sure the measuring tape is parallel to the floor and exert enough pressure so as to try to minimize the affect of your clothing. If you are measuring in inches then round your measurement down to the nearest ½ inch (45 3/8 inches becomes 45 inches, for example). Repeat a few times until you find you are taking a consistent measurement.

Notes
  1. Hodgdon, J.A. and M.B. Beckett (1984) Prediction of percent body fat for U.S. Navy men from body circumferences and height. Report no. 84-11, Naval Health Research Center, San Diego, CA;
  2. Hodgdon, J.A. and M.B. Beckett (1984) Prediction of percent body fat for U.S. Navy women from body circumferences and height. Report no. 84-29, Naval Health Research Center, San Diego, CA.
  3. DoD Instruction 1308.3, "DoD Physical Fitness and Body Fat Programs Procedures," November 5, 2002