Crib to toddler bed...

For those of you who converted your crib to a toddler bed, how long was your toddler able to sleep in it before outgrowing it??? I'm having another baby, and due my my first baby is 2. I was thinking about putting her in a bed, BUT unless she's climbing out there's really not reason to other then for the new baby. So, I'm seriously considering getting another crib.