Our top tips for picking a basketball? Beginners, kids and anyone looking to improve should opt for smaller balls that are easier to hold onto, pass and catch, while experts who want to play proper games will need a full-size one (size 7). At Decathlon, we believe that sport is for everyone and you don't have to spend a lot to get involved, which is why we've kept our prices low. But for the most dedicated fans, we also stock some special NBA-approved basketballs.