The body mass index is a standard method of evaluating body weight in relation to height. But it isn't simply a ratio of your weight to height. That corresponds to the numbers on the U.S. government's weight table. The Canadian guidelines for healthy weight mark the upper cutoff at a BMI of 27, the point at which there's a high risk of serious health problems. Bear in mind that the BMIs, weight tables, and other indices serve only as an approximate guide to what you should weigh.
Many factors come into play.
In addition, where your body fat is stored affects your health risks.