How Big Should My Bunny's Cage Be?
When getting a cage for your bunny, it is important to remember that the cage needs to accommodate the size that the rabbit will grow to, not necessarily the size that the bunny is at the time you buy the cage. There are different rules for different cages, but the main deciding factor in cage size is whether your bunny is going to be an indoor bunny or an outdoor bunny. It is recommended that your bunny is an indoor bunny, because, like cats, bunnies are much happier, more friendly, and develop more personality when they live inside than outdoor rabbits do. Outdoor rabbits tend to become quite frightened and skittish, not allowing themselves to be petted or touched, and normally dying a great deal earlier than house rabbits, and all alone outside.
Indoor rabbits can be house trained, and so can be let out to run about at supervised times. This means that their cages need not be as big as outdoor bunnies, which need large amounts of space to be happy. An indoor bunny cage should be large enough for your bunny to lay down in comfortably, with a corner to spare for droppings, and a space for food. Because your bunny will get lots of exercise when it is out, and mostly use the cage for sleeping, it does not need to be all that large, though it should not be cramped either. Ensure that your bunny has more than enough room to flop and do a big bunny stretch out along the side of the cage.
Outdoor rabbits are often kept in small hutches. If you plan to keep your rabbit in one of these, please do not get a rabbit. Not only are you depriving it of company by leaving it outside, but you are also depriving it of room to move and frolic. Rabbits love to run and play, and yes, to jump. If you must keep your bunnies outdoors, then make sure that the cage and run has enough room for them to be able to jump upwards around two feet, and enough room lengthwise to get a good bunny sprint on, at least five feet long by five feet wide, and preferably larger. Yes there are a great many tiny rabbit hutches and cages sold on the market, but these are sold by people who know next to nothing about proper rabbit care, and probably don't give a damn either, they are only after your money, and pay little regard to the pet's welfare.
I have an outdoor cage for my own bunny, but she lives indoors most of the time, and the cage is only used to give her a spot of fresh air outside on occasion. The cage is three feet high and has a floor space of around 15 square feet. This would still be too small to keep her in all the time.
Think of your bunny's health and happiness when it comes to buying a cage, and if this all seems like too much of a hassle, then get a goldfish.