While the height difference between a 5'9" and a 6'1" person is only 3 inches, it's actually a lot simpler to be around this height for two reasons. First, your arms don't have to be exactly 24 inches from your body in order to reach the top of the backboard. Second, as long as you're at least three feet off the ground, your body will experience less than half of its maximum potential jumping height. The answer depends on how far up you want to be able to shoot the ball. If you can catch it with your hand above the rim, then you can shoot it. Otherwise, you're just wasting your energy. The best way to learn how high you can jump is by taking measurements of yourself when you're standing still. Then add one foot to each measurement and see what happens. For example, if your standing height without shoes is 29 inches and adding 1 foot makes you reach 30 inches, that's enough to clear the rim. You should be able to shoot balls out of play from beyond the three-point line. This means you need to be able to jump at least 36 inches. The more important factor here is your leg strength. You need to make sure you can push off with both legs and get enough power to fly through the air.