Rat Cage Calculator

by Monika
Rat cage size calculator

Rat Cage Calculator: Check How Many Rats Can Live In a Cage

Rats should ideally have at least 2.5 cubic feet of cage volume per rat to be comfortable and to avoid any aggression or fighting. Use this rat cage calculator to figure out the maximum number of rats a cage can house. Remember that this rat cage calculator gives you a maximum number of rats for the dimensions you entered – so if it says a cage is suitable for 4 rats, it means it is not suitable for more than 4, not that 4 rats wouldn’t be more comfortably housed in a larger cage.

How Much Space Do Rats Need?

Ideally, a rat cage should have a volume of over 8 cubic feet, even if you have only 2 rats. Most pet rats will spend the majority of their time in their cage – sometimes up to 22 or 23 hours a day. So, it needs to be big enough to give them plenty of space to explore and express their natural behaviors. Aim to give your rats a complete environment, with lots of different areas to dig, tunnel, climb, run, sleep and forage for food.

Another important aspect of the cage to look at is the floor space. In the wild, rats spend a lot of their time running, so a cage should give them enough floor space to jog around. A cage should have a minimum of 24 inches (60 cm) in one direction. A good floor area would be at least 32×20 inches (80×50 cm) or more.

Optimal Bar Spacings

Another crucial thing to look at when buying a rat cage, along with the cage size, is the bar spacing. Bar spacing that is too large would allow your rat to escape or hurt themselves.

The best bar spacings for rats are 0.4 – 0.6 inch (1 – 1.5 cm). These are small enough to keep young rats and small females in. Whether you have horizontal or vertical bars is a matter of human taste – rats happily climb either.

Cages with bar spacings of 0.8 – 1.0 inch (2 – 2.5 cm) can sometimes be used for adult rats, especially males, but they can be risky with smaller animals. Rats can fit through any gap they can get their heads through.

Using the Cage Space Wisely

Getting your cage set-up right is as important as choosing the right size cage.

Most cages come with a few basics like shelves, a hammock and maybe a house. However, these are rarely enough to keep rats entertained. Domestic fancy rats are Rattus norvegicus, a species that digs extensive burrows in the wild, but also climbs buildings and trees, and can travel several hundred meters to find food. So, a cage to keep rats happy and healthy is a cage set-up for:

  • digging: fill the cage base with suitable materials, digging boxes
  • climbing: ladders, ropes, fruit tree branches
  • running: silent spinners, flying saucers

Popular Rat Cages & Their Dimensions

The cage volume is not the only thing to look at. While the cage volume might be suitable due to a good length and width of the cage, there’s also a minimum height to take into consideration. According to animal welfare organizations, at absolute minimum, rats should be able to stand up on their hind legs and still have a bit of space over their heads. But we don’t want to settle for a bare minimum and want to enable our rats to climb and explore so we suggest a height of 20 in (50 cm) or more, if possible.

Here are some of the most popular rat cages, their dimensions, bar spacings, and their ratty capacity. These are affiliate links.

Critter Nation Two Story Rat Cage

MidWest Homes Two Story Rat Cage
  • Dimensions: 36 x 24 x 54 inches (27 ft³)
  • Bar spacing: 0.5 in
  • Can house up to 10 rats
  • Sold on: Amazon & Chewy

Critter Nation Single Story Rat Cage

MidWest Homes Single Story Rat Cage
  • Dimensions: 36 x 24 x 24.5 inches (12.25 ft³)
  • Bar spacing: 0.5 in
  • Can house up to 4 rats
  • Sold on: Amazon & Chewy

Ferplast Ferret Tower Two-Story Cage

Ferplast Ferret Tower Two-Story Cage
  • Dimensions: 29.5 x 31.5 x 63.4 inches (ft³)
  • Bar spacing: 0.5 in
  • Can house up to 13 rats
  • Sold on: Amazon & Chewy

Prevue Hendryx Feisty Ferret Home

Prevue Hendryx Feisty Cage for Rats
  • Dimensions: 31 x 20 x 41.5 inches (14.89 ft³)
  • Bar spacing: 0.87 in – for adult rats only
  • Can house up to 5 rats
  • Sold on: Amazon

Prevue Rat and Chinchilla Cage

Prevue Rat and Chinchilla Cage
  • Dimensions: 31 x 20.5 x 30 inches (11 ft³)
  • Bar spacing: 0.37 in
  • Can house up to 4 rats
  • Sold on: Amazon & Chewy

Kaytee My First Home

Kaytee My First Home Rat Cage Calculator
  • Dimensions: 30.5 x 18 x 30 inches (9.53 ft³)
  • Bar spacing: 0.5 in
  • Can house up to 3 rats
  • Sold on: Amazon & Chewy

Since you’ll be cleaning the cage at least once a week, you’ll want to get a cage that is easy to clean. Your back and shoulders will thank you for it.

Cages with large doors make it easy to access all parts of the cage so you’ll have no problem replacing the bedding, sweeping out the poops, or changing the litter trays. Cages such as Critter Nation allow the front to fully open which makes the cleaning so much easier.

What Kind of Rat Cages to Avoid?

Cages advertised for rats AND mice are usually too small for rats, as rats are much bigger and need more space.

Avoid these types of cages:

  • Wooden cages: wood absorbs rat pee which will make the cage smell bad pretty soon and it will be almost impossible to clean. Not only that, but rats will have no problem making a hole in the wood with their little teeth and escaping the cage.
  • Glass or plastic tanks: glass, plastic, and similar materials provide very poor ventilation which is a recipe for disaster when it comes to rats. Rats are prone to respiratory disease and they need plenty of fresh air flow in their living area. Plus, glass and plastic tanks limit your rats’ activity as they can’t climb like they can in the barred cages.

Cages with metal bars are the optimal solution as they allow the air to circulate and there is no risk of a runaway rat if the bar spacing is small enough.


Keep in mind that this rat cage size calculator shows the maximum number of rats a cage can house, but your rats would benefit from a cage that is larger than the minimum size they can fit in! A spacious cage that is well set-up is a dream home for rats.

1 comment

Anne May 1, 2022 - 5:06 am

I love the Critter Nation cage, my rats have so much room to enjoy and it’s so easy to clean compared to my old cage which was a nightmare!

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