Body Fat Calculator
Estimate body fat percentage using the US Navy tape measurement method. Only requires a soft tape measure.
How the Navy Body Fat Method Works
The US Navy circumference method estimates body fat percentage from simple tape measurements. For men, it uses height, neck, and waist. For women, it adds hip circumference. The formulas were derived by correlating these measurements with hydrostatic weighing results across thousands of military personnel, giving a reasonably accurate estimate without expensive equipment.
The key advantage over BMI is that it distinguishes between fat and muscle to some degree. A muscular person with a narrow waist and thick neck will score lower body fat than someone with the same weight but a larger waist - which better reflects reality. The main limitation is that fat distribution varies between individuals, so the formula is less accurate for people who carry fat differently from the military average used to derive it.
Frequently Asked Questions
How accurate is the Navy body fat formula?
The US Navy method is accurate to within 3-4% of DEXA scan results for most people. It is less accurate at very low body fat percentages (below 8% for men, below 16% for women) and for individuals with unusual fat distribution patterns. It is significantly more accurate than BMI for assessing body composition.
Where exactly do I measure waist circumference?
Men: measure at the narrowest point of your abdomen, usually at or just above the navel. Women: measure at the narrowest point of the waist, typically between the lower rib and the top of the hip bone. Keep the tape horizontal and parallel to the floor.
Where do I measure neck circumference?
Measure just below the larynx (Adam's apple), with the tape perpendicular to the long axis of the neck. Keep your head level and do not flex your neck muscles. Take the measurement at the narrowest point.
What body fat percentage should I aim for?
For men: essential fat is 2-5%, athletic is 6-13%, fit is 14-17%, average is 18-24%, obese is 25%+. For women: essential fat is 10-13%, athletic is 14-20%, fit is 21-24%, average is 25-31%, obese is 32%+. Athletes typically aim for the athletic or fit range.
Can I use this calculator to track progress?
Yes - consistency matters more than absolute accuracy. As long as you measure in the same way each time (same time of day, same conditions), changes in your result reliably reflect real changes in body composition over weeks and months.