Your BMI is an objective scientific measure, that uses your height and weight. You can calculate your BMI by dividing your weight in kilograms by the square of your height in meters.
One variable BMI fails to consider is lean body mass. It is possible for a healthy, muscular individual with very low body fat to be classified obese using the BMI formula.
If you are a trained athlete, your weight based on your measured percent body fat would be a better indicator of what you should weigh.