What’s your body fat percentage? Most fitness enthusiasts want to know their body fat percentage, since it’s one of the four components of body composition—the other three being body mass, fat mass, and fat free mass. Too much body fat results in obesity and increased waist circumference, which could increase risk for cardiovascular disease.

There are several ways to estimate body fat, and we’ve gotten to the bottom of them. Here’s everything you need to know about estimating your body fat percentage, and—depending on your lifestyle and fitness goals—trying to decrease it.