A hutch alone is never enough for a rabbit, no matter how big it is, because rabbits are built to run, jump, binky, and dig. An exercise run gives them that daily movement, and without it muscles weaken, bones thin, and boredom turns into bar chewing and aggression. This free rabbit run size planner turns rabbit count into a minimum run area and a daily free-roam target, so you can plan a run that actually lets rabbits behave like rabbits.
The area rule is three square metres per rabbit as a minimum, which sounds generous until you watch a rabbit sprint. Three square metres is roughly a run of two metres by one and a half metres for one rabbit, and it doubles to six square metres for two. That space must be usable, flat, and safe, not a narrow corridor, since rabbits run in bursts and need a straight stretch to build speed. A run that is long and thin fails even if its total area looks right on paper.
Using the tool takes seconds. Enter the number of rabbits that will share the run, say whether you have a secure garden, and press Plan run size. You will see the minimum area in square metres and the recommended free-roam hours per day, which is three hours for one rabbit and four hours for two or more, since bonded pairs play and chase each other and use more time well. The tip line changes with your garden answer, so indoor-only owners get a room-based plan.
Safety decides whether a run is usable at all, and size means nothing if the run is not secure. Outdoor runs need a solid roof against cats, foxes, and birds of prey, mesh with gaps too small for a rabbit head, and either a buried skirt or a solid floor so rabbits cannot dig out and predators cannot dig in. Check latches daily, since rabbits learn to nose at weak catches, and never leave a run unsupervised in extreme heat or storms.
What goes inside the run matters as much as its walls. A cardboard tunnel, a digging box filled with soil and hay, a hay rack, a water bowl, and a hideaway turn empty space into a rabbit playground, and rotating the toys every few days keeps the space interesting. Scatter herbs in hay for foraging, add a low platform for jumping, and keep one shaded corner always available, since rabbits overheat fast and need a cool retreat even on mild days.
Indoor free-roam time needs the same planning as an outdoor run. Rabbit-proof the room by covering cables, blocking gaps behind furniture, removing toxic plants, and protecting skirting boards, then let the rabbit out for the recommended hours each day. Indoor runs made from pen panels work well in small homes, and they can join onto the hutch so the rabbit chooses when to run and when to rest. Supervised time counts, but all-day access is far better.
Bonded pairs and groups change the maths in a good way. Two rabbits use a run better than one, since they chase, groom, and rest together, but they also need two of everything inside it: two hideaways, two water sources, and two hay spots, so one rabbit cannot guard all the resources. Introduce new rabbits on neutral ground and watch for chasing that turns aggressive, since a run that is too small makes bonding much harder and can break a fragile bond.
This planner gives minimum exercise guidance for healthy adult rabbits, and young, very active, or giant rabbits will enjoy more space and more hours. It never replaces a vet or rescue assessment of your setup, and it assumes the run is used daily, not only at weekends. It is free, it needs no sign-up, and it runs entirely in your browser, so you can replan the run whenever your rabbit family grows.