This simple BMI calculator lets you choose between Metric and imperial system, and it displays the appropriate units of measurement according to the measurement system you selected.
You can then, select your height and weight from the dropdown menus provided to check your Body Mass Index.
You can see the BMI score displayed on top. If you want the interpretation of the result or you want to know more about Body Mass Index, you can check this site or any other authoritative website:
So if you want to monitor your weight, I think you will find the BMI calculator useful.