Unless I'm confused, it's not at all difficult to do the calculations by hand.
You multiply the L x W x H (make sure everything is in inches), which gives you the total cubic inches
If you divide that by (12 x 12 x 12), you get the number of cubic feet
Finally, divide that by 2 or 2.5 (your minimum amount of space per rat) and that gives you the number of rats the cage can hold.
Example: Double Unit Critter Nation
Manufacturer states that the unit measures 36â³L x 24â³W x 63â³H, but it's on a 10" stand, so the actual cage measurements are closer to 36â³L x 24â³W x 53â³H
So, 36 x 24 x 53 = 45792 cubic inches
45792 / (12 x 12 x 12) = 26.5 cubic feet
26.5 / 2 = 13.25
So, the Double Unit Critter Nation can hold 13 rats, giving each one 2 cubic feet of space.
Or, if you want to make sure each rat has 2.5 cubic feet of space, it can hold ( 26.5 / 2.5 = 10.6 ) about 10 rats.
