๐ช Body Fat Calculator
* This is an estimate based on the US Navy circumference method and may differ from a body composition scale's measurement.
Estimate your body fat percentage without a body composition scale, using just a tape measure. Based on the US Navy circumference method, this tool uses your height and the circumference of your neck and waist (plus hips for women) to give you an approximate body fat percentage and category.
How to use
- Select your gender.
- Enter your height and the circumference of your neck and waist in cm (and hips, for women).
- Your estimated body fat percentage and category are shown automatically.
How the calculation works
This tool estimates body fat with the circumference method used by the US Navy (the Hodgdon and Beckett equations), which relies on the tendency for the waist to grow relative to the neck as body fat increases. Measurements are in centimetres. Men: 495 รท (1.0324 โ 0.19077 ร logโโ(waist โ neck) + 0.15456 ร logโโ(height)) โ 450 Women: 495 รท (1.29579 โ 0.35004 ร logโโ(waist + hip โ neck) + 0.221 ร logโโ(height)) โ 450 The 495 and 450 come from the Siri equation, which converts body density into body fat percentage. Categories follow the American Council on Exercise (ACE) bands: for men, under 6% essential fat, under 14% athletes, under 18% fitness, under 25% average, and above that obese (for women, 14%, 21%, 25% and 32%).
Worked example
A man, 175 cm tall, neck 38 cm, waist 85 cm 495 รท (1.0324 โ 0.19077 ร logโโ(47) + 0.15456 ร logโโ(175)) โ 450 โ 16.9% โ fitness category A woman, 160 cm tall, neck 32 cm, waist 72 cm, hips 96 cm, comes to about 27.8%, in the average category.
Things to be aware of
- This is a simple estimate from circumferences; technique can shift the result by a few percent.
- Measure the waist at the navel, the neck just below the Adam's apple and the hips at their widest, keeping the tape level.
- Measuring under the same conditions (such as first thing in the morning) makes changes easier to compare.
- Body composition scales and clinical methods work differently, so their figures may not match.
FAQ
How accurate is this method?
The US Navy method is a simple circumference-based estimate and can differ from results using a body composition scale or hydrostatic weighing. Treat it as a rough guide.
Where exactly should I measure?
Measure the neck just below the larynx, the waist at the level of the navel, and the hips at their widest point, keeping the tape horizontal.
Does a high or low body fat percentage directly indicate health?
Body fat percentage is just one indicator of body composition. If you have concerns, consult a healthcare professional or use a dedicated measurement device.