Most size recommendation on the internet or at stores are less than adequate for your rabbit. With the exception of the Marchioro Tommy K 120 (and even this is suited for only smaller rabbits), most commonly sold rabbit cages are just too small. A life in a cramped cage with inactivity leads to behavioral and medical issues. Here are a few guidelines for choosing a cage size. If in doubt, go larger. If you have a rabbit that falls on the upper end of the weight guide, go to the next larger size. Some breeds of rabbit may be slim and racy with a lighter weight than a similar sized rabbit but need the next cage. Belgian Hares, for example, are a lean, racy breed have a lighter weight compared to their size (6 - 9 lbs) but require a larger cage than a seven-pound English Angora.
Small Rabbits (approx 2 - 4 lbs)
No smaller than 24x24 inches
Medium Rabbits (approx 4 - 6 lbs)
No smaller than 24x30 inches or 30x36 inches
Larger-Medium Rabbits (6 - 9 lbs)
No smaller than 30x36 inches
Large Rabbits (9 - 11 lbs)
No smaller than 30x36 or 30x48 inches
Giant Rabbit (over 11lbs)
No smaller than 30x48 inches
If you have a bonded pair of bunnies in a cage, you will need to go at least the next size up. Since rabbits can be litter trained, for giant rabbits, a portable dog exercise pen on a solid floor is another option if you cannot find a large enough rabbit cage.
Combined with a properly sized cage, pet rabbits must have time outside the cage in a rabbit-proofed room.
For more information:
K. W. Cages
www.kwcages.com
House Rabbit Society
www.rabbit.org