Mini Skateboard Deck width: 7.0″ with an average deck length of 28”. Mini decks are the best skateboards for beginners who are 6-8 years old, between 3’5” and 4’4” tall who wear size 4-6 shoes. Mid-size Skateboard Deck width: 7.3”+ with an average deck length of 29”. For skaters 9 to 12 years old between 4’5” and 5’2” tall who wear size 7-8 shoes.