Answer
How big should a hamster cage be?
At least 12 × 12 × 20 in with bars no more than 0.5 in apart, per MSPCA-Angell. MSPCA’s US minimum is a 12 × 12 × 20 in cage or a 20-gallon tank. European welfare guidance asks for far more floor space, so treat this as the floor, not the goal.
Minimums at a glance
| Animal | Minimum (L × W × H) | Bars |
|---|---|---|
| Hamster | 12 × 12 × 20 in | 0.5 in |
| Gerbil | 20 × 20 × 12 in | – |
| Mouse | 12 × 12 × 20 in | – |
| Rat | 24 × 24 × 24 in | 0.5 in |
| Chinchilla | 30 × 24 × 15 in | – |
| Ferret | 24 × 24 × 48 in | – |
MSPCA’s US minimum is a 12 × 12 × 20 in cage or a 20-gallon tank. European welfare guidance asks for far more floor space, so treat this as the floor, not the goal.
More questions
Can two hamsters share a cage?
Syrian (teddy bear) hamsters must live alone; some dwarf species share, but fights are common.
Is a tank OK for a hamster?
A 20-gallon tank is MSPCA’s minimum alternative to a wire cage, with a mesh lid.
Is a bigger cage better for a hamster?
Yes: these are minimums, and welfare groups agree that more space is better.
How do I measure a hamster cage?
Use the inside floor dimensions, not the outside of the base or the box size.
Do levels or shelves count as floor space?
Extra levels add enrichment, but most guidance is based on the main floor area.
How much time should a hamster spend outside the cage?
Many small pets need daily time out of the cage; rabbits, chinchillas and ferrets need hours of extra space a day.
Can I check my own hamster cage?
Yes: enter its inside length, width and height in the cage size calculator.
Where do these minimums come from?
From the welfare and veterinary sources linked below.
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