How big will my cactus get?

Question:I purchased a cactus from the florist section in the supermarket. It is in a 5" tall pot and it stick out about 5" from the dirt. Will it get much bigger, how big, and if so, when should I change the pot?

Answers:
You don't even tell us what it is. Some grow tall, some get rounder, but they all grow... in time

Find out what it is first. If the rootball looks compacted and tight, then by all means repot it in good cactus mix.