A good way to see whether or not you are at a healthy weight is by calculating your Body Mass Index. Your Body Mass Index takes into account your height and your weight to tell you whether or not you are the right weight for your height. Obviously, taller people can afford to carry more weight than shorter people.

If you search "Body Mass Index chart" or "BMI chart" on an internet search engine, a number of clear and easy to use charts will appear. All you need to do is identify your weight along one side of the chart, and your height along the other side of the chart, and you will be able to see whether or not you are at a healthy weight. On the other hand, searching for a "Body Mass Index Calculator" will bring up a variety of calculators which allow you to type in your height, weight, gender and other features, to tell you if you are overweight, underweight, or just right. However, online calculators may use different formulas to deduce your Body Mass Index, so charts tend to be a more reliable option.

If we say that the average height of a 12 year old boy is approximately 5ft, then a healthy weight is anything between around 100 and 120lb according to Body Mass Index charts.