BMI Calculator Use this calculator to check your body mass index (BMI). Height cm. Please enter value between 125 and 225. Weight kg. Please enter value between 10.0 and 500.0 ( one decimal ). Height ft. in. Please enter value between 4.2 and 7.3 Weight lb. st. Please enter value between 22.0 and 1000.0 ( one decimal ). Use this calculator to check your body mass index (BMI), which can be a helpful tool in determining your weight category. Or, use it to calculate your child’s BMI.