A garage that is “big enough” on paper can be impossible to use if you cannot open the doors or walk around the car. This calculator sizes the interior from the number of cars, their dimensions and the clearance you want, and gives the door width.
How the calculation works
- Width = cars × car width + (cars + 1) × side clearance
- Depth = car length + 2 × front and back clearance + workbench or storage depth
- Single door width = cars × car width + (cars − 1) × side clearance
- One door per car = car width + about 2.5 ft
Car widths here are measured on the body, with the mirrors folded. A midsize sedan is about 6 ft wide and 16 ft long; a full-size pickup can be 6.7 ft wide and 19 to 20 ft long.
Example
Two cars 6.5 ft wide and 16 ft long, with 3 ft between them and the walls, need an interior 22 ft wide. With 3 ft in front and behind, the depth is 22 ft, for 484 sq ft. A single 16 ft door, or two 9 ft doors, fits both cars.
Common garage sizes
| Garage | Minimum | Comfortable |
|---|---|---|
| One car | 12 × 20 ft | 14 × 24 ft |
| Two cars | 20 × 20 ft | 24 × 24 ft |
| Three cars | 30 × 20 ft | 36 × 24 ft |
The minimum sizes fit small cars with little room to spare. For pickups, large SUVs or storage, plan 24 ft or more of depth.
Clearance guidelines
- Between cars and walls: 3 ft lets you open doors and walk past; 2 ft is tight.
- In front: 3 ft for walking around; more if a workbench, freezer or water heater sits there.
- Height: 8 ft ceilings are standard; 10 to 12 ft allow storage racks or a car lift.
- Doors: standard single doors are 8 or 9 ft wide and 7 ft tall; doubles are 16 ft wide. A 9 ft door is more forgiving for wide vehicles.
Before you build
Check local zoning for setbacks, maximum lot coverage and height, and whether a building permit is needed. Plan electrical outlets, lighting and, if you drive or plan to buy an electric car, a 240 V circuit for a charger.