A cage should be at least 4 times the size of your bunny when he’s
entirely stretched out–more if he is confined for a large amount of the
day. One guideline to go by is at least 8 square feet of cage time
combined with at least at least 24 square feet of exercise space, for
1-2 rabbits, in which the rabbit(s) can run and play at least 5 hours
per day. You can build or buy your rabbit a two-storey “condo” with the floors connected by a ramp–they love this!