I did this a year ago. Turned out great. A few tips.
– I used the Rustoleum brand. The "2 car garage" box was enough for my 2-car garage. Amazing, eh? I even put it on relatively thick.
– make sure you can’t see concrete after you roll it. you should only need one coat.
– BE EASY ON THE CONFETTI. YOU WILL RUN OUT BEFORE YOU COVER THE WHOLE FLOOR. I had to go up to Home Depot and bribe them out of another bag of the stuff. I don’t suggest that. It comes with 2 bags, and that should be enough. I put too much on.