Body Fat Calculator
Use this free Body Fat Calculator to calculate your Body-fat percentage instantly and accurately.
Measurements (cm)
Body fat
What is a Body Fat Calculator?
A Body Fat Calculator estimates your body fat percentage using circumference measurements. It uses the US Navy method, which is a practical and reasonably accurate way to assess body composition at home.
How to calculate body fat manually (the formula)
The US Navy method uses different formulas for each sex. For men: body fat % = 495 ÷ (1.0324 − 0.19077 × log(waist − neck) + 0.15456 × log(height)) − 450. For women: uses waist, hip, neck, and height.
Example calculation
A man with height 178 cm, neck 38 cm, waist 86 cm: body density = 1.0324 − 0.19077 × log(48) + 0.15456 × log(178) = 1.0324 − 0.320 + 0.347 = 1.0594. Body fat = 495 ÷ 1.0594 − 450 = 17.2%.
Common mistakes
- Measuring at the wrong location — Waist must be measured at the navel level, neck below the larynx, and hips at the widest point. Wrong placement skews results.
- Pulling the tape too tight or loose — The measuring tape should be snug against the skin but not compressing it. Consistency in tension matters for tracking changes.
- Measuring after eating or exercise — Body measurements change throughout the day. Measure first thing in the morning for the most consistent results.
Frequently asked questions
What is body fat percentage?
Body fat percentage is the proportion of your total weight that comes from fat. It is a better indicator of fitness and health than weight or BMI alone.
How is body fat percentage calculated?
The calculator uses the US Navy circumference method. For men: uses height, neck, and waist measurements. For women: adds hip measurement. It calculates body density and converts to body fat percentage.
What is a healthy body fat percentage?
Essential fat is 2 to 5% for men and 10 to 13% for women. Athletic ranges are 6 to 13% for men and 14 to 20% for women. Healthy ranges extend higher.
How accurate is the US Navy method?
The US Navy method is fairly accurate for most people, with an error margin of about 2 to 3% compared to DEXA scans. Consistency in measurement technique matters more than absolute accuracy.
Can I measure body fat at home?
Yes, this calculator uses circumference measurements you can take at home. For best results, measure first thing in the morning and use consistent landmarks on your body.