Baby Care Boutique

I am considering purchasing a toddler size quilt. I realize I can use this in the crib and then use it in the toddler bed (when I transition from the crib to the bed). The crib converts into a toddler bed with the same size mattress. What I want to know is how old children are when they are too big/too tall to fit in the toddler bed and need a regular twin bed. I am trying to figure out how many years worth of use I will get out of this quilt before it is too small. The quilt would be too small for a twin bed but perfect for a toddler bed.