Standard Garage Size

A one-car garage starts at 12 by 20 feet. A two-car starts at 20 by 20. A three-car starts around 32 by 22. Those are the floors, not the comfortable sizes, and the difference between the two is usually depth rather than width. Measure yours with the calculator, then compare it against the tables below.

Garage sizes at a glance

Garage	Minimum	Common	Square feet (common)
One car	12 x 20 ft	14 x 24 ft	336 sq ft
Two car	20 x 20 ft	24 x 24 ft	576 sq ft
Three car	32 x 22 ft	36 x 24 ft	864 sq ft
Four car	40 x 20 ft	24 x 45 ft	1,080 sq ft

One-car garage

The standard one-car garage is 12 feet wide by 20 feet deep, which is 240 square feet. That fits a car and very little else.

Dimensions	Square feet	What it holds
12 x 20 ft	240 sq ft	One car, nothing else
12 x 24 ft	288 sq ft	One car plus a workbench at the end
14 x 24 ft	336 sq ft	One car with room to open both doors
12 x 30 ft	360 sq ft	One car plus real storage depth

Twelve feet of width is tight. Once a car is centered, you have about two feet on each side, which is enough to get out but not enough to carry a bag past the mirror without turning sideways. Fourteen feet is the width where a one-car garage stops feeling like a car-shaped box.

Two-car garage

This is the one everyone searches for. The minimum is 20 feet wide by 20 feet deep, or 400 square feet, and 24 by 24 at 576 square feet is the size most builders now treat as standard.

Dimensions	Square feet	Notes
20 x 20 ft	400 sq ft	The minimum. Two cars, no storage
22 x 22 ft	484 sq ft	Room to walk between the cars
24 x 24 ft	576 sq ft	The common modern standard
20 x 30 ft	600 sq ft	Narrow but deep, good for a workbench
24 x 30 ft	720 sq ft	Two cars plus a real shop bay

At 20 feet wide, two mid-size cars leave roughly 2 feet between them and about 2 feet on each outside wall. Door dings are guaranteed. At 24 feet, you get about 3 feet of space in each gap, which is the difference between a garage you park in and one you use.

Three-car and four-car garages

A three-car garage runs 32 feet wide by 22 deep as standard, with 36 by 24 the more comfortable size.

Garage	Dimensions	Square feet
Three car, standard	32 x 22 ft	704 sq ft
Three car	32 x 24 ft	768 sq ft
Three car, comfortable	36 x 24 ft	864 sq ft
Three car, with shop	36 x 28 ft	1,008 sq ft
Four car, minimum	40 x 20 ft	800 sq ft
Four car, deep	24 x 45 ft	1,080 sq ft

Note that a 36 by 28 three-car garage at 1,008 square feet is bigger than plenty of apartments, and close to half the floor area of an average new US home. It is still not living area, which is the point of does a garage count as square footage.

A tandem garage is a different layout for the same problem: two cars nose to tail in a single deep bay, usually 12 by 36 or so. It counts as a two-car garage in a listing but only has one door, and getting the inside car out means moving the outside one.

Depth is the number that matters

Width decides how many cars fit. Depth decides whether the garage is useful.

Many full-size pickups are close to 20 feet long. Park one in a 20 foot deep garage and the tailgate is against the door and the bumper is against the back wall, with nothing behind it. A mid-size sedan at roughly 16 feet leaves 4 feet, which is a bike, a bin, and not much more.

Depth	What it leaves behind a full-size truck	Behind a sedan
20 ft	Essentially nothing	About 4 ft
22 ft	About 2 ft	About 6 ft
24 ft	About 4 ft, enough for shelving	About 8 ft, a workbench
30 ft	A full workshop bay	A full workshop bay

If you're choosing between 2 extra feet of width and 2 extra feet of depth on a new build, depth is almost always the better buy.

Garage doors

Door sizes are more standardized than the buildings they go in. A single door is 8 to 10 feet wide, a double is 16 feet, and heights run 7 to 8 feet.

Door	Size	Opening area
Single, standard	9 x 7 ft	63 sq ft
Single, wide	10 x 7 ft	70 sq ft
Double	16 x 7 ft	112 sq ft
Double, tall	16 x 8 ft	128 sq ft

Eight foot doors matter if you own a truck with a roof rack, a van, or a lifted vehicle. That opening area is also a big deduction when you're estimating siding or paint for that wall, which standard door sizes and the wall calculator both handle.

Measuring your own garage

Measure the inside, wall to wall at floor level, and multiply length by width. That gives the slab area. A 24 by 24 garage is 576 square feet.

Two things to watch. Bump-outs for a water heater, furnace, or stair landing come out of the usable area, so measure those separately and subtract them. And if you're comparing to a listing, check whether the figure quoted is the slab or the exterior footprint, which includes wall thickness and runs 20 to 40 square feet higher on a typical two-car garage.

The rectangle calculator above gives you the perimeter as well, which is what you need for baseboard, trim, or the wall area for insulation and drywall.

Common mistakes

Assuming a two-car garage fits two cars comfortably. At the 20 by 20 minimum, it fits two cars and nothing else, including the doors you need to open.

Counting garage square footage as living area. It never counts, attached or not, finished or not, unless it's been properly converted.

Forgetting the door swing on the house side. The entry door into the house needs clear floor, and it usually lands right where you want shelving.

Sizing for today's car. Vehicles have grown. A garage built in the 1960s for a sedan of the era is often too short for a current crossover.

Frequently asked questions

What is the standard garage size?

A one-car garage is 12 by 20 feet, a two-car is 20 by 20 at minimum with 24 by 24 now common, and a three-car starts around 32 by 22 feet.

How many square feet is a 2 car garage?

400 square feet at the 20 by 20 minimum, and 576 square feet at the common 24 by 24. Most two-car garages fall between 400 and 720 square feet.

What are the dimensions of a 2 car garage?

20 by 20 feet is the minimum, 22 by 22 is comfortable, and 24 by 24 is the modern standard. Width matters most for door clearance between the cars.

How many square feet is a 3 car garage?

704 square feet at the standard 32 by 22, rising to 864 at a comfortable 36 by 24. With a workshop bay, three-car garages pass 1,000 square feet.

How deep should a garage be?

Twenty feet is the minimum and 24 feet is the useful size. A full-size pickup is close to 20 feet long on its own, so a 20 foot deep garage leaves nothing behind it for storage or a workbench.

What is the standard garage door size?

Nine feet wide by 7 feet tall for a single door and 16 by 7 for a double. Eight foot tall doors are common where trucks or vans need the clearance.

How many square feet is a 1 car garage?

240 square feet at the standard 12 by 20. A more usable one-car garage at 14 by 24 is 336 square feet.

Does garage square footage add to my home's square footage?

No. Garage area is reported separately from living area no matter how it's finished, which is the rule explained in does a garage count as square footage. A properly permitted conversion is the only route to counting it.

Sources

Standard garage size guide, Alan's Factory Outlet