Body Mass Index (sometimes abbreviated as BMI) is a number that results from a mathematical calculation that is based on how much you weigh as well as how tall you are. To figure out your Body Mass Index, you can do the following calculation:
So, for example, if someone weighs 163 pounds and is five foot two inches (62 total inches), that will look like this:
163 x 703 = 114,589
then you take that total and divide it by your height, in inches:
114,589 / 62 = 1848.2
In this example I rounded the answer to the nearest tenth for convenience. Then, that total gets divided by your height in inches one more time:
1848.2 / 62 = 29.8
So, in this case, the answer is 29.8. This is the Body Mass Index. Find your number in the chart below and you'll see where, according to your Body Mass Index, you are, health-wise.
While you can find your Body Mass Index fairly easily, there are a few things you'll need to know if you're going to use it as a basis for weight loss or gain. First of all, it doesn't take into account whether you have an "unusual" build. For example, a senior citizen may have lost muscle mass, so his or her weight would need to be adjusted for that loss. An athlete may have more muscle than the average person for whom this formula was created. In that case, that person's body weight would need to be higher than what is estimated here for that person to be healthy.
Calculating the BMI in this way is also to be used for adults only. It is best to talk to your doctor about how much your child should weigh, as often their advice will be to keep them from gaining any more weight and let them grow into their heft.