Rat Care
Rat Cage Size & Fit Calculator
Enter your cage’s inside size, bar gap and number of rats to see how it compares with Blue Cross, Woodgreen and RSPCA guidance.
Your result will show here. The size table below gives the same guidance.
Measure the space your rats can use
This rat cage size and fit calculator checks your cage against published care guidance. Enter the inside width, depth and height, the gap between the bars, and the number of rats. Choose centimetres or inches for all four measurements. The result tells you how many rats the cage is big enough for, and checks the bar gaps separately.
Measure the usable enclosure, not its packaging or overall height on a stand. Width and depth describe the floor; height is the living space above it. Measure the clear gap between bars, not the distance between their centres. If the cage is divided into separate homes, check each home separately. Do not add disconnected compartments together.
How the fit check works
Blue Cross recommends at least 90 cm long, 60 cm deep and 120 cm high for two to five rats. Woodgreen gives 80 × 50 × 80 cm for up to four, and 93 × 63 × 123 cm for up to ten. We use the larger Blue Cross dimensions for smaller groups, then Woodgreen’s larger benchmark for six to ten. All three dimensions must meet the relevant benchmark; extra height cannot replace a narrow floor.
The result is a supported group range, not a precise maximum occupancy. We do not stretch those figures to guess a number for bigger groups: even a very large cage shows “up to ten”, and larger groups need individual advice.
Check the bars as well as the size
Woodgreen specifies 1 cm bar spacing. This checker uses 1 cm or less. A wider gap stops a positive fit result even when the dimensions pass. The RSPCA says gaps must prevent a rat putting its head through. Check doors, corners and damaged bars too; a number alone cannot confirm that your particular rats cannot escape.
A worked example
A cage with 90 cm inside width, 60 cm depth, 120 cm usable height and 1 cm bar gaps meets the smaller-group benchmark for five rats. The same cage is too small for six to ten. A 120 cm tall cage with only 50 cm depth also fails the smaller-group check: height does not make up for missing floor space.
Check without the calculator
| Group | Width × depth × height | Bar gap |
|---|---|---|
| 2–5 rats | At least 90 × 60 × 120 cm | 1 cm or less |
| 6–10 rats | At least 93 × 63 × 123 cm | 1 cm or less |
| More than 10 | Individual assessment needed | Check for each rat |
What this cannot check
Dimensions are only one part of a suitable home. Rats need company, ventilation, solid floors, shelter, enrichment and safe routes between levels. Blue Cross recommends pairs or groups; Woodgreen ideally recommends at least three. Enter one rat and the checker reminds you that rats need company. Age, mobility, relationships and the furnished layout may change what suits your rats. Ask a rat-experienced rescue or vet about special needs. Shelves and hides do not turn an undersized cage into a suitable one.
