How do you know what size of dirt bike to buy?

Talk with a salesman, let them help determine what size dirt bike is appropriate for your. Be sure to tell them what you will be doing, play riding, racing, dual sport rides, etc. Select a model that is suitable for your skill level taking into account the bike's handling, power and size. Sit on the bike to make sure it is the right size and test ride each bike. Also, consider buying a used dirt bike.