How big a cage does a budgie need? Measure yours against the wingspan rule

How big a cage does a budgie really need? The RSPCA sizes it by wingspan: at least twice the wingspan in height, width and depth for a group of budgies, with a little extra for every bird beyond two.

Enter your birds and your cage's measurements, and get a pass or fail on each side, a bar-gap check and a comparison with the vet-manual minimum. It also covers why width beats height, where to place the cage and why time out of it still matters. Sources are the RSPCA and veterinary guides.