Body Fat Calculator
The Body Fat Calculator estimates your body fat percentage using the US Navy method, which requires only height, neck, and waist measurements. Body fat percentage is a more accurate measure of fitness than BMI because it distinguishes between fat and muscle mass. This calculator works for both men and women and provides categories from essential fat to obese. For most accurate results, measure yourself in the morning before eating.
Formula
US Navy Method: Men: %BF = 86.010 x log10(waist - neck) - 70.041 x log10(height) + 36.76 Women: %BF = 163.205 x log10(waist + hip - neck) - 97.684 x log10(height) - 78.387 All measurements in cm log10 = base-10 logarithm
Example
Male, height 178 cm, neck 38 cm, waist 85 cm: %BF = 86.010 x log10(85 - 38) - 70.041 x log10(178) + 36.76 %BF = 86.010 x log10(47) - 70.041 x log10(178) + 36.76 %BF = 86.010 x 1.672 - 70.041 x 2.250 + 36.76 %BF = 143.8 - 157.6 + 36.76 = 22.9% Category: Acceptable
How to Use
- Enter your gender, height, neck, and waist measurements
- Women also enter hip measurement
- The calculator uses the US Navy method
- Review your body fat percentage and category
- Compare with healthy ranges for your gender
Frequently Asked Questions
What is a healthy body fat percentage?
For men: 10-20% is healthy (athletes 6-13%). For women: 18-28% is healthy (athletes 14-20%). Essential fat minimums are 2-5% for men and 10-13% for women. Below essential fat is dangerous.
How accurate is the US Navy method?
The US Navy method is reasonably accurate (within 3-4% of DEXA scans) for most people. It is less accurate for very muscular or very lean individuals. For the most accurate measurement, use DEXA, hydrostatic weighing, or Bod Pod.
How do I measure my waist and neck?
Measure waist at the navel (belly button) and neck just below the larynx (Adam's apple). Keep the tape measure level and snug but not compressing the skin. Measure in the morning before eating for consistency.
Is body fat percentage better than BMI?
Yes, body fat percentage is more accurate than BMI because it distinguishes between fat and muscle. A muscular athlete may have a high BMI but low body fat. Body fat percentage directly measures what BMI estimates indirectly.
Can I reduce body fat without losing weight?
Yes. By building muscle while losing fat, your weight may stay the same while your body fat percentage decreases. This is called body recomposition. It requires strength training and adequate protein intake.