Small birds also require a large space for the exercise they need.
Some are several “rules of thumb” for measuring least cockatiel cage size.
There is a rule which is that the width of the cage should be at least twice the wingspread length. It is tall enough to adjust the long tails of cockatiel parrots. Albino Cockatiel, White Faced Cockatiel and Types of White-Faced Cockatiel also, need same space.