★ CONSTRUCTION · GARAGE · SIZE CHART
A 2-car garage is 20 by 20 feet — 400 square feet with a 16 foot door. A 1-car garage is 12 by 20 feet, 240 square feet, with an 8 foot door. Pick your cars and storage below.
Standard garage depth is 20 feet; width sets the size. A car needs about 8 to 10 feet of width with room to open its doors, so a 1-car garage is 12 feet wide, a 2-car is 20 feet wide, and each extra car adds about 10 feet. This calculator picks the footprint for your cars and adds width for storage.
Garage depth is almost always 20 feet: a car is about 15 to 16 feet long, and 20 feet leaves room to walk around the front and back. Width is what sets the size. A car needs about 8 to 10 feet of width with room to open its doors, so a 1-car garage is 12 feet wide, a 2-car garage is 20 feet wide, and each extra car adds about 10 feet. The door is 8 feet for one car, 9 feet for a comfortable single, 16 feet for two cars side by side (or two 8 foot doors), and 16 feet plus 8 feet for three. Storage adds width at the same 20 foot depth: every 20 square feet of storage is one extra foot of width, rounded up to a whole foot.
At the defaults — 2 cars and 0 sq ft of storage — the garage is 20 × 20 ft, which is 400 sq ft, with a 16 ft door (or two 8 ft doors). The slab is the same 400 sq ft. That is 200 sq ft per car.
| Garage | Footprint (ft) | Sq ft | Door width(s) | Typical use |
|---|---|---|---|---|
| 1-car | 12 × 20 | 240 | 8 ft (9 ft comfortable) | One car with room to open the doors; tight for storage. |
| 1.5-car | 16 × 20 | 320 | 9 ft | One car plus a motorcycle, bikes or a workbench. |
| 2-car | 20 × 20 | 400 | 16 ft (or two 8 ft) | Two cars side by side; the most common size. |
| 2.5-car | 24 × 20 | 480 | 16 ft + 8 ft | Two cars plus a third bay for a motorcycle or workshop. |
| 3-car | 30 × 20 | 600 | 16 ft + 8 ft | Three cars; or two cars plus a full workshop. |
| 4-car | 40 × 20 | 800 | Two 16 ft | Four cars; or three cars plus a workshop and storage. |
Setup: 2 cars, extra storage 0 sq ft.
Line 1 — the base size. The 2-car row of the chart is 20 ft wide and 20 ft deep, so the footprint is 20 × 20 ft.
Line 2 — the area. 20 × 20 = 400 sq ft. That is 200 sq ft per car.
Line 3 — the door. The 2-car row takes a 16 ft door, or two 8 ft doors if each car is to have its own opening.
Line 4 — the storage. 0 sq ft of storage adds 0 ÷ 20 = 0 ft of extra width, so the footprint stays 20 × 20 ft.
Line 5 — the slab. The slab is the footprint: 400 sq ft of concrete.
Storage example: 2 cars plus 100 sq ft of storage needs 100 ÷ 20 = 5 ft of extra width, so the garage is 25 × 20 ft and 500 sq ft, with the same 16 ft door.
Reverse: the most cars that fit in 500 sq ft is 2.5 cars (480 sq ft footprint); in 600 sq ft it is 3 cars (600 sq ft); in 1,000 sq ft it is 4 cars (800 sq ft); in 399 sq ft it is 1.5 cars (320 sq ft). A 24 × 20 ft garage leaves 80 sq ft of storage after 2 cars (480 − 400), and a 30 × 20 ft garage leaves 200 sq ft (600 − 400).
1 car: the garage is 12 × 20 ft, 240 sq ft, with an 8 ft door. That is 240 sq ft per car — room to open the doors, but little left for storage.
1.5 cars: the garage is 16 × 20 ft, 320 sq ft, with a 9 ft door. The extra 4 feet of width holds a motorcycle, bikes or a workbench beside the car.
2.5 cars: the garage is 24 × 20 ft, 480 sq ft, with 16 ft + 8 ft doors. Two cars under the 16 ft door, and a third bay under the 8 ft door.
3 cars: the garage is 30 × 20 ft, 600 sq ft, with 16 ft + 8 ft doors. Three cars side by side need 30 feet of width; the 8 ft door takes the third car.
4 cars: the garage is 40 × 20 ft, 800 sq ft, with two 16 ft doors. That is 200 sq ft per car, the same as the 2-car garage.
2 cars + 100 sq ft storage: 100 ÷ 20 = 5 ft of extra width, so the garage is 25 × 20 ft and 500 sq ft, with the same 16 ft door. Storage adds width, never door width.
2 cars + 200 sq ft storage: 200 ÷ 20 = 10 ft of extra width, so the garage is 30 × 20 ft and 600 sq ft — the same footprint as a 3-car garage, used for storage instead of a third car.
1 car + 50 sq ft storage: 50 ÷ 20 = 2.5 ft, rounded up to 3 ft of extra width, so the garage is 15 × 20 ft and 300 sq ft, with the same 8 ft door. The rounding adds 10 sq ft of slack: the garage holds 60 sq ft of storage, not 50.
3 cars + 75 sq ft storage: 75 ÷ 20 = 3.75 ft, rounded up to 4 ft of extra width, so the garage is 34 × 20 ft and 680 sq ft, with 16 ft + 8 ft doors.
2 cars + 25 sq ft storage: 25 ÷ 20 = 1.25 ft, rounded up to 2 ft of extra width, so the garage is 22 × 20 ft and 440 sq ft, with the same 16 ft door.
Reverse — the other way round: the most cars that fit in 500 sq ft is 2.5 cars (480 sq ft); in 600 sq ft it is 3 cars (600 sq ft); in 1,000 sq ft it is 4 cars (800 sq ft); in 399 sq ft it is 1.5 cars (320 sq ft). A 24 × 20 ft garage leaves 80 sq ft of storage after 2 cars, and a 30 × 20 ft garage leaves 200 sq ft.
The model assumes a standard depth of 20 feet for every size, and that the widths in the chart are the common standard sizes: 12, 16, 20, 24, 30 and 40 feet. It assumes storage adds width at the same 20 foot depth, one foot of width per 20 square feet, rounded up to a whole foot — so a small storage ask can add a foot more than the arithmetic needs. It assumes the slab area is the footprint, with no apron or driveway included. It assumes the door widths are the standard ones in the chart and that a 16 foot door can be swapped for two 8 foot doors. It does not cover ceiling height, door height, setbacks, or local building code — check those with your local code before you build. Rounding convention: feet are whole numbers, areas are whole square feet, and all figures are computed from unrounded values, rounded only for display.
| Output | Formula | What it means |
|---|---|---|
| Recommended footprint | width × 20 ft (chart + storage width) | 20 × 20 ft. |
| Total area | width × 20 ft | 400 sq ft. |
| Door width | chart row for the cars | 16 ft door (or two 8 ft doors). |
| Width | chart width + extra width | 20 ft. |
| Depth | 20 ft, standard | 20 ft. |
| Extra width for storage | ceil(storage ÷ 20) | 0 ft. |
| Storage | as entered | 0 sq ft. |
| Slab area | footprint area | 400 sq ft. |
| Area per car | total area ÷ cars | 200 sq ft. |
| Max cars for 500 sq ft | largest chart row ≤ 500 sq ft | 2.5 cars (480 sq ft). |
| Max cars for 600 sq ft | largest chart row ≤ 600 sq ft | 3 cars (600 sq ft). |
| Max cars for 1,000 sq ft | largest chart row ≤ 1,000 sq ft | 4 cars (800 sq ft). |
| Max cars for 399 sq ft | largest chart row ≤ 399 sq ft | 1.5 cars (320 sq ft). |
| Storage allowance in a 24 × 20 ft garage (2 cars) | 480 − 400 | 80 sq ft. |
| Storage allowance in a 30 × 20 ft garage (2 cars) | 600 − 400 | 200 sq ft. |
| 1 car | same model, 1 car | 12 × 20 ft, 240 sq ft, 8 ft door. |
| 1.5 cars | same model, 1.5 cars | 16 × 20 ft, 320 sq ft, 9 ft door. |
| 2.5 cars | same model, 2.5 cars | 24 × 20 ft, 480 sq ft, 16 ft + 8 ft doors. |
| 3 cars | same model, 3 cars | 30 × 20 ft, 600 sq ft, 16 ft + 8 ft doors. |
| 4 cars | same model, 4 cars | 40 × 20 ft, 800 sq ft, two 16 ft doors. |
| 2 cars + 100 sq ft storage | same model, +100 sq ft | 25 × 20 ft, 500 sq ft, 16 ft door. |
| 2 cars + 200 sq ft storage | same model, +200 sq ft | 30 × 20 ft, 600 sq ft, 16 ft door. |
| 1 car + 50 sq ft storage | same model, +50 sq ft | 15 × 20 ft, 300 sq ft, 8 ft door. |
| 3 cars + 75 sq ft storage | same model, +75 sq ft | 34 × 20 ft, 680 sq ft, 16 ft + 8 ft doors. |
| 2 cars + 25 sq ft storage | same model, +25 sq ft | 22 × 20 ft, 440 sq ft, 16 ft door. |
The math is exact for the numbers you enter: the area is the width times the 20 foot depth, and the extra width is the storage divided by 20, rounded up to a whole foot. What the chart cannot do is know your cars: check that a 12 foot 1-car garage fits your car with the doors open, because a full-size truck is longer and wider than a sedan. It assumes a standard depth of 20 feet and the standard widths in the chart, and it leaves out ceiling height, door height, setbacks and local building code. It assumes the slab is the footprint, with no apron or driveway. For what the concrete costs, see concrete calculator; for another size chart in the same style, see dumpster size chart.
Bright Side Kit. "Garage Size Chart: 1, 2, 3 & 4 Car Dimensions 2026." https://brightoolbox.com/garage-size-chart/ Accessed October 25, 2026.20 by 20 feet — 400 square feet — with a 16 foot door. That is the most common size: two cars side by side, 200 sq ft per car. Two 8 foot doors work instead of one 16 foot door if each car is to have its own opening.
12 by 20 feet — 240 square feet — with an 8 foot door. That leaves room to open the doors, but little left for storage. A 9 foot door is the comfortable single-car width if the car is wide.
30 feet. A 3-car garage is 30 by 20 feet, 600 sq ft, with a 16 ft door plus an 8 ft door. Each car takes about 10 feet of width, so three cars need 30 feet.
It depends on the footprint. A 24 by 20 ft garage leaves 80 sq ft of storage after 2 cars (480 minus 400), and a 30 by 20 ft garage leaves 200 sq ft. Or build wider: every 20 sq ft of storage adds one foot of width at the same 20 ft depth.
2.5 cars. The largest standard size that fits in 500 sq ft is the 2.5-car garage at 24 by 20 ft, which is 480 sq ft. A 3-car garage needs 600 sq ft. In 399 sq ft the most that fits is 1.5 cars.
8 feet per car at minimum. One car takes an 8 ft door (9 ft is comfortable), two cars take a 16 ft door or two 8 ft doors, and three cars take a 16 ft door plus an 8 ft door. Storage never changes the door width — only the footprint.