A standard one-car garage is about 12 ft. wide and somewhere between 20 and 24 ft. deep. Each additional car will add between 8 and 10 ft. to the initial width, meaning a large 2-car garage may be about 20 ft. wide by 20 to as much as 24 ft. deep. A standard height for a finished garage is usually 7 or 8 ft. More info about garages can be found here.