How many square feet is their in a three car garage?

Answer 1

There is no correct answer because a garage for three cars can be as large as one wants; however, it can never be smaller than the footprint of the cars (plus some "wiggle room" so you can open the door and get out). Of course not all cars have the same footprint and most garages also have space for storage, a workbench, etc.

Just for grins, let's toss out an assumption that you need about 200 square feet per car. For a three car garage that equals 600 square feet.