Body Mass Index (BMI) is weight (mass) in kilograms divided by the square of height in meters. I wrote this little applet in 2002 because the web forms back then were annoying. Adjust the vertical slider to your height and the horizontal slider to your weight.
| Green - normal: | [18.5, 25) |
| Yellow - overweight: | [25, 30) |
| Orange - obese: | [30, 40) |
| Red - extremely obese: | [40, ...) |
Note that these ranges are for adults. For kids see BMI For Children at the CDC.
For more information see BMI: Body Mass Index at the Centers for Disease Control.
But, beware. Wikipedia also says it is contoversial.