Your parrot's cage would be the house and where he will spend a lot of his hours, and that means you have to be certain it's big enough to match his requirements. Truly, the larger the cage you're able to provide, the better (there is no such thing as too large in regards to birdcages), however, the minimal dimensions will be dependent on your bird's size.
Your parrot's cage must offer horizontal space (length and depth) of at least two to three times his wingspan and vertical distance (elevation) at least one-and-a-half times the height of your bird from the top of his head to the tip of his tail.