How do I know when my child needs a new ski boot size?

Check fit at the start of every season by removing the liner and having the child stand on it. If their toes extend past the front of the liner by more than a half inch, or if their heel lifts noticeably inside the buckled boot, it's time for a new size. Also watch for complaints of toe pain (too small) or difficulty controlling skis (too big). Children's feet can grow a full size or more in a single growth season, so never assume last year's boots still fit.