BMI Calculator – Comparing height and weight
 
A good indication of a healthy weight is based on comparing your height with your weight. This is known as body mass index (BMI). Your BMI takes your overall size into account, so it's a good indicator of your total amount of body fat. It's also a reliable predictor of how likely you are to be affected by conditions associated with being too heavy (or too light).
 
It's worth remembering however that muscle weighs more than fat. So, someone's BMI could be within the normal range, but they could be carrying too much fat. Equally, someone could be heavily muscled and have little body fat, but their BMI could be above the normal range.