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The Fun Mouse: Mouse Information: Cage Calculator

Due to people not reading this page in its entirety and making assumptions they should not, the calculator has been altered. Unfortunately people didn't realize that it is set as a *minimum* amount of space per well-bred mouse (mice that are not of premium lineage are different). It was set up for a minimum number for breeders and is definitely acceptable, if not MORE space than many other calculators out there. That said, no matter what, all calculators will be debated for many reasons, one of which is that opinions will always vary. Do also note that some people think the space recommended is too small simply because they don't understand what a mouse needs or how to set up housing space. Mice love to climb and do NOT need open (bare) floor space (with the exception of elderly or otherwise physically impaired mice), contrary to popular belief. A mouses tank SHOULD look cramped full of stuff! It should be full of a million toys, low as well as high up! Everywhere a mouse goes it should be an activity. The largest open space in a mouses tank should be the bed, which should only be slightly larger than the mice next to each other. If you have beef with this cage calculator, you may want to look into your tank design before aiming your anger here ;) ;)

In the calculator below, type in the dimensions, in inches, of the Floor space you want to put mice into.
Height doesn't matter as long as you can fit a wheel in there. While shelves can be very fun for your mouse they don't count as floor space because it's not common living quarters. While some mice will spend a lot of time on shelves, it still irrelevant for an array of reasons. Mice sometimes don't feel as safe and secure on shelves (though they do like to play on them if encouraged), especially in cages with bars. They generally spend a majority of their time on the floor space. When using a tank, ventilation can be an issue where shelves are concerned, even with a mesh lid. Adding many mice to a tank requires more ventilation. While you can add shelves, you can't add more ventilation to a tank. This can also cause condensation which can lead to ill mice. If you add shelf space into the calculator and it says you can add 2 times as many mice (or more), you could run into an extreme ventilation problem. Putting this into real life terms: you can fit a maximum of 3 fancy mice into a 10 gallon tank. If you add a shelf to this, it doesn't mean that you can now add 3 more mice, making a total of 6 mice in a 10 gallon tank. This is not adequate space or ventilation by any means. For safety reasons, it's best not to add shelf space to floor space for an over all calculation. It could really cause great harm.

This calculator supports your average sized pet shop fancy mouse, weighing around 25 grams. Larger mice *need* more floor space than an average pet shop fancy. Click here to see the size difference (mouse pictured on left is 60g, mouse on right is 25g). Additionally, the calculator only takes into account the average activity level of a fancy mouse. Some mice are less active and some more. More active mice *need* more space. This calculator is only presented to you for a rough idea of mice per square inch of floor space. You still *must* use your judgment because mouse personalities do play a large roll in tank size.

STOP! Did you READ this page or scroll down here to plug in numbers?! You MUST read this page before assessing the number of mice per tank!

Cage Calculator

Length of home:
Width of home:
(height and shelves are irrelevant)
# of Mice:

Round down decimals. For instance, 1.6 means 1 mouse, not 2.
Scroll down for calculations of standard tank sizes.
Please note that this is set forth as a minimum.
More space is greatly encouraged! Why provide your mice the minimum #? Go with more ;). It's not a contest to see how many will fit.

Quick look up of tank dimensions

Gallons Size # of Mice
5 1/2 16 x 8 1*
10 20 x 10 3
15 24 x 12 4
20 H 24 x 12 4
20 L 30 x 12 5
29 H 30 x 12 5
30 H 30 x 12 5
30 L 36 x 18 9
40 H 36 x 18 9
40 L 48 x 13 9
50 H 36 x 18 9
50 L 48 x 18 13
55 48 x 12 8
60 40 x 16 9
75 48 x 18 13
90 48 x 18 13
100 60 x 18 16

* TFM doesn't recommend 5g tanks (or their equivalent in floor space for any habitat) for long term use by pet caregivers.
* Housing more than 2 dozen mice together, no matter the size of the habitat, isn't recommended.

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