What are the usual dimensions of a two car and a three car garage?

Answer 1

2 car 20x20, better yet is 24x24

3 car 30w x 24 give or take.

Comment:

20x20 (400 ft2) barely accommodates two of today's cars, and leaves very little room for anything else such as snow blower (for us in the snow belt) or lawnmower. Opening the card doors can even be dangerous. A 20x20 foot print also typically limits you to one garage door.

A 24x24 (576 ft2) garage provides almost 50% more space than 20x20. Accommodates two large cars plus storage, lawn maintenance, snow removal gear, etc..

For a 3-car, a 24' depth is good. A 30' width for 3 cars is nowhere near as bad as 20' for 2 cars, but can still be tight if you need to store other items. Consider 32', 34', and 36' widths. 36' is pretty large; at above 36' width you begin to create a monster.