What is the measurement for a cage?
How to Measure Your Cage – NatureChest
If you have a square or rectangular bird cage, you will need to measure each side at the widest point, and then add all four sides together to get the total circumference of your cage. For example if your cage measures 20×20, the total circumference would be 80 inches in size.

What is a good bird cage size?
Cage Size | Pittsburgh | P.E.A.R.L. Parrot Rescue
Birds use the width of their cage more than they use the height, and the cage should be twice the width of the bird’s wingspan.” Bird Cage Portal and Kings Cages have the exact same recommendation on their websites: “At the very minimum the width of the cage should be 1-1/2 times as wide as your bird’s wingspan.