A hutch that looks big in a shop can still be far too small for a rabbit that lives in it, and size is the single most common housing mistake rabbit owners make. Rabbits need room to take several full hops in a row, to stand up fully on their back legs without touching the roof, and to lie stretched out flat. This free rabbit hutch size calculator turns rabbit body length and rabbit count into minimum length, width, height, and total floor area, so you can judge a hutch before you buy it.
The rule behind the numbers is simple and based on the rabbit itself. Minimum hutch length is three times the rabbit body length, with a floor of one hundred and fifty centimetres, and minimum width is twice the body length, with a floor of sixty centimetres. Height is at least sixty centimetres so the rabbit can sit upright with ears up. Floor area then follows from length times width, multiplied by the number of rabbits, since each extra rabbit needs its own full share of space.
Using the tool is straightforward. Measure the rabbit from nose to tail base in centimetres while it lies relaxed, enter that length and the number of rabbits that will share the hutch, and press Calculate hutch size. A thirty five centimetre rabbit kept alone, for example, needs a hutch at least one hundred and fifty centimetres long, seventy centimetres wide, and sixty centimetres high, giving just over one square metre of floor. Two such rabbits need double that floor area in total.
Minimum is not the same as ideal, and bigger is always better for rabbits. The figures here are the smallest size that allows normal movement, not a generous home, and a hutch that only just meets the minimum still needs daily free-roam time outside it. If you can afford a larger hutch, a shed conversion, or a pen attached to the hutch, take it, since rabbits kept in cramped hutches develop muscle weakness, boredom, and behaviour problems that no toy can fix.
Hutch layout matters almost as much as raw size. One end should hold a dark, draught-free sleeping area with deep bedding, the other end should hold hay, water, and a litter box, and the middle should stay open for movement. Ramps between levels do not count as floor area, and steep ramps are a fall risk for young or senior rabbits. Solid floors beat wire floors, which injure feet and cause sore hocks, so cover any wire with a solid board.
Indoor rabbits need the same maths, even if the hutch is only a base camp. A pen or a rabbit-proof room counts as living space only if the rabbit can reach it all day, not only for an hour in the evening. If the hutch door stays shut for most of the day, the hutch itself must meet the full minimum, and the run or room time is a bonus on top. Measure the space the rabbit actually lives in, not the space it visits.
Common buying mistakes are easy to spot once you know the numbers. Tiny pet shop hutches marketed for rabbits are often built for hamsters in disguise, with lengths under one metre that fail the three times rule for any real rabbit. Multi-level hutches look generous in photos but give little usable floor, and hutches with attached runs count the run only if the rabbit can enter it at all times. Always measure in centimetres and check the figures before paying.
This calculator gives minimum housing guidance for healthy adult rabbits, and young, giant, or disabled rabbits may need more space or a different layout. It never replaces welfare guidance from a rabbit vet or rescue, and it assumes the hutch is cleaned daily and paired with exercise time. It is free, it needs no sign-up, and it runs entirely in your browser, so you can recheck sizes before every purchase or adoption.