Garage Dimensions: 1, 2 & 3-Car Sizes and Door Widths

A typical two-car garage is about 20 × 20 ft at the small end and 24 × 24 ft when you want room to open doors and store things; a one-car garage is about 12 × 20 ft and a three-car garage about 32 × 22 ft. None of these is a code minimum. The building code says little about garage size, and the right figure depends on your vehicles, the door you choose and how much else the garage has to hold.

Below are the working sizes, the door options, a measured two-car garage from a real house plan, and the few code rules that do apply.

Garage sizes at a glance

These ranges are inside dimensions commonly used by builders and designers. They are rules of thumb, not requirements.

The width figures come from simple arithmetic. A mid-size car is about 6 ft wide without mirrors; a full-size SUV or pickup is closer to 6 ft 8 in to 7 ft. Add about 3 ft beside each driver door to get out without dinging the other car, and about 2 ft along the outside walls. Two cars need roughly 20 ft at the bare minimum and 22 to 24 ft to be comfortable.

Depth: check your longest vehicle

Depth is where garages most often fall short. Many sedans and small SUVs are 15 to 16 ft long, but full-size crew-cab pickups commonly run 19 to 21 ft or more depending on cab and bed. Add about 3 ft in front for walking past the hood, and more for a workbench, a freezer or a step up into the house. For a large pickup, plan on 24 ft inside or deeper. Measure your own vehicles rather than trusting a model name; the same truck is sold in several lengths.

Garage door sizes

A 7 ft tall door is the long-standing standard; an 8 ft door clears roof racks and taller trucks and needs a correspondingly taller ceiling and header. Two single doors use more wall than one double but leave a post between the cars, which some people like for parking. Whatever you choose, the door opener and track need clear ceiling space above the door: allow at least a foot of headroom above the door height, more for some opener types.

A two-car garage in a real plan

The attached garage in FloorGen's 3-bed ranch with 2-car garage template is drawn 22 × 24 ft on its wall grid and measures 507 ft² of net floor area inside its walls, right in the comfortable band above. It has a 16 ft opening for a double door facing the street, a window on the side wall, and a 32 in door at the back into the laundry and mudroom, so groceries and muddy boots come into a utility room rather than straight into the kitchen.

With two cars parked, the 24 ft depth leaves a few feet in front of the hoods for a shelf or a walkway to the house door. That door sits at the back corner, away from where the car doors swing, which is the detail that makes a 22 ft wide garage feel bigger than its size.

If you are converting a garage rather than parking in one, the smaller 2-car garage to studio ADU template starts from a 20 × 20 ft shell, the bare-minimum two-car size. The garage conversion floor plans post shows what fits in it. The ranch itself is covered in ranch house floor plans.

The code rules that apply

The International Residential Code, which most US jurisdictions adopt with local amendments, does not set a minimum garage size (see standard room sizes). It does regulate how an attached garage is built. Section numbers here are from the 2021 IRC.

• Floor: garage floors must be an approved noncombustible material, and the parking area must slope to a drain or toward the main vehicle door, so leaked fuel and oil run out rather than toward the house (2021 IRC R309.1).
• Door into the house: a door between the garage and the dwelling must be solid wood or solid or honeycomb-core steel at least 1⅜ in thick, or a 20-minute fire-rated door; recent editions also require it to be self-closing or automatic-closing, a provision some states amend. A garage may not open directly into a room used for sleeping (2021 IRC R302.5.1; see garage fire separation code).
• Wall and ceiling to the house: the garage side of walls and ceilings shared with the dwelling needs gypsum board, at least ½ in on walls, and ⅝ in Type X on the ceiling where habitable rooms are above (2021 IRC R302.6).
• Ducts and penetrations: ducts that pass through the separation need to be steel of a minimum gauge and may not open into the garage, and other penetrations must be sealed (2021 IRC R302.5.2 and R302.5.3).

Ceiling height and storage

The IRC's 7 ft ceiling rule applies to habitable rooms, not to garages, but a practical garage ceiling is usually 8 to 10 ft: enough for a 7 or 8 ft door, its opener and track, and overhead storage racks. Ceiling-mounted storage needs clearance above the open door and the car roof. Wall storage is easier to plan: a 2 ft deep shelf along the back wall takes 2 ft of depth, which is the main reason to choose 24 ft over 22 ft.

Planning the garage in FloorGen

Draw the garage as a room and FloorGen labels its net area; drop in cars from the catalog to test the parking, and use the tape measure to check the space beside each door. The IRC code profile flags doors that swing into furniture and walkways narrower than about 30 in, which catches a car parked too close to the house door. It does not check fire separation, floor slope or zoning, so take the list above to your building department.