What size cage do I need?

I made this mistake before and trust me its heartbreaking to see your little baby rat growing up so big and not being able to move as much as s/he should. The best way to put it is you should spend about 90 to 100 dollars for a cage for your two rats because rats are always better in pairs and should I have someone to spend their life with. Each rat should have a minimum of 2 cubic feet of space, so the cage should be at least 30w30h18L. For maximum room for their toys and hide out spaces hammocks and all that type of stuff including your pets. The bottoms should be solid. NO WIRE BOTTOMS. Please do not use an aquarium due to the lack of ventilation that your rats will need.
THE CAGE ON THE RIGHT IS NOT A GOOD SIZE!!!!!




THE ONE ON THE RIGHT IS NOT A GOOD SIZE!!!!
(My personal story experiences buying a cage)
I went to the pet store to buy a cage for my little one and the store owner told me that this cage would be fine for about 7 months and boy was he wrong. After 3 months of having her I had to buy a new one. picture above to show the size difference. I am so upset I had not did more research about the cage size. I had looked up everything but this and needless to say its embarrassing but people need to know space is the best thing for your rat and their safety is their priority to you. Its worth the money please just buy the larger cage.