If you're not sure about size, measure the space you expect to place the cage - twice. If you're not a numbers person, lay some masking tape on the floor or cut a large piece of paper or cardboard illustrating the size of the cage and lay it on the floor.

Dimensions do not include seed guards. Typically add 8 inches side-to-side and 8 inches front-to-back. This will vary between manufacturers but is a good rule of thumb.

Dimensions below are generally expressed in inches. The first number is the cage side-to-side. The second number is the cage front-to-back. There are one or two exceptions (only to save the number of sizes)

Birds live a long time, the cage will occupy it's space a long time, did I mention measure twice?