Body Fat Calculator
Calculate body fat percentage
About the Body Fat Calculator
Body fat percentage tells you more about composition than weight or BMI ever can — two people at the same weight can carry very different amounts of fat and muscle. This calculator estimates yours using the US Navy circumference method, which needs only a tape measure rather than calipers or a scan.
Fitness-minded people use it to track recomposition that the scale hides, when fat drops while muscle holds steady. Because the method relies on body measurements — neck, waist, and for women also the hips — alongside height, it gives a usable estimate at home without specialized equipment.
How to Use the Body Fat Calculator
- Select your sex (this changes which measurements and formula are used).
- Enter your height in centimeters.
- Measure and enter your neck and waist circumference in centimeters.
- If you are female, also enter your hip circumference.
- Read your estimated body fat percentage, calculated with the US Navy method.
Why Use ToolForge’s Body Fat Calculator
- It uses the US Navy circumference formula, so all you need is a tape measure — no calipers, scales, or lab equipment.
- It applies the correct sex-specific equation, including hip circumference for women, rather than a one-size-fits-all estimate.
- It reports a body composition figure that BMI cannot, distinguishing fat from overall weight.
- Measurements are processed in your browser and never uploaded.
Frequently Asked Questions
How accurate is the US Navy body fat method?
It is a reasonable estimate for most people and tracks changes well over time, but it is not as precise as a DEXA scan or hydrostatic weighing. Accurate, consistent tape measurements matter — measure at the same spots each time for reliable trend tracking.
Where exactly do I measure?
Measure the neck just below the larynx, the waist at the navel for men and at the narrowest point for women, and the hips at the widest point for women. Keep the tape snug but not compressing the skin, and stand relaxed.
What is a healthy body fat percentage?
Healthy ranges differ by sex and age, but general fitness guidelines often cite roughly 10–20% for men and 18–28% for women, with athletes typically lower. These are broad references, not medical thresholds, so consider them alongside other health markers.
Why does the female calculation need hip measurement?
The US Navy formula for women includes hip circumference because fat distribution differs by sex, and adding the hip measurement improves the estimate's accuracy. The male formula uses only neck and waist.
