What changes the budgie questions answer
Width matters more than height because budgies move side to side and need usable flight space. Tall skinny cages look large to people but often give birds less practical room.
Use safe bar spacing
Budgie bars should be close enough that the bird cannot push its head through. For most budgies, half-inch spacing or smaller is the safer shopping target; also check door gaps, feeder doors, and loose hardware.
Leave open movement space
A cage packed with perches and toys is not roomy anymore. Use a few well-placed natural perches, separate food and water, and a small toy rotation while keeping clear paths for movement.
Plan for the real day
If the budgie is in the cage for long workdays, buy larger than the bare minimum. Out-of-cage time helps, but it does not make a cramped home base okay.
Skip the pretty trap
Round cages, tall narrow cages, rusty cages, and cages with unsafe spacing are poor choices even when the listing says parakeet.