Naturally, the width of the garage door depends almost entirely on the size of the cars housed within the structure; the bigger the car, the wider the door. Single Garage Door. Typically, a single garage door will have a width of 8, 9 or10 feet wide. The more compact the car, the smaller the width of the door should be. Of course, most new homes are built with doors that are around 10 feet wide simply because bigger SUV-style vehicles are more popular.