While most of the options on our list do already come with an exercise ball, you may want to eventually look at getting one that suits you better than the factory option. If you are able to test the balls out beforehand to ensure the aforementioned 90-90 rule is in play, that is the most ideal way of ensuring you get the right size for your height. If you don’t have access to a number of different sized exercise balls, there are some general guidelines that take your height into effect. If you’re less than 5 feet, a 45 cm ball should work for you. If you’re between 5’1” and 5’8”, you should look at trying a ball that is 55 cm. Folks between 5’9” and 6’2” can try an exercise ball that is 65 cm while those who are between 6’3” and 6’7” can get away with a 75 cm option.