Rats like to live in groups and you should buy the biggest cage you can afford and if your new to keeping rats I would recommend getting a trio to start off with.

Your cage should give each rat around 2 square foot of space. You can use cage calculators like the one on fancy-rats, but these are only to be used as a guide to help you decide. Remember, you owe it to your pets to give them a comfortable and happy home, not just the minimum they can survive in. Rats kept in a large and enriched environment with both ratty and human interaction will develop more character and make better pets.

A few guide to cage buying:
1. Buy the best cage you can afford to suit the rats and you.
2. Watch out for bar spacing - some rabbit, ferret and bird cages have bar spacing over 1" which is easy for most does and kittens to escape from.
3. Male rats tend to like more floor space where as female rats like to climb.
4. Some rats will chew plastic so those with plastic bases may need replacing.
5. Rats require cages to suit their requirements which vary throughout their lives. Cages suitable for young kittens may not be suitable for adult or elderly rats.

I have broken this list down in to sections to try and make it easy to see the cages that are available.

Some places you could try and get a 2nd hand cages:
www.ebay.co.uk
www.preloved.co.uk
www.gumtree.co.uk

At the bottom of this page are some pictures of cages which are UNSUITABLE for rats but are sold as rat cages!