Garage size by vehicle: sizing one, two, and three bays

Planning workflow

1. Measure the actual vehicles, including mirrors, and note how far each door opens.
2. Add side clearance per vehicle for door swing and for walking between vehicles.
3. Add front clearance for the walking route and for anything mounted on the front wall.
4. Add rear or side depth for storage, mechanical equipment, and a workbench if you want one.
5. Check the door opening width and height against the widest and tallest vehicle, not the average one.

Formula or decision logic

Interior width = sum of vehicle widths + side clearance x (number of vehicles + 1). A workable planning clearance is 30 in per gap for comfortable door opening and 24 in as a tight minimum. Interior depth = vehicle length + front walking clearance + rear storage depth. Door opening width must exceed the vehicle width plus mirror width plus a driving tolerance; a nominal 16 ft double door serves two vehicles far better than two 8 ft doors with a post between them, but the post carries load and cannot simply be deleted.

Worked planning example

Two vehicles at 6 ft 4 in and 6 ft 8 in wide need 13 ft of vehicle width. Three 30 in gaps add 7 ft 6 in, giving 20 ft 6 in of interior width - wider than a 20 ft nominal double garage, which is why two cars plus open doors so often do not fit. On depth, a 16 ft 6 in vehicle plus 3 ft of front walking space plus 2 ft of rear shelving needs 21 ft 6 in of interior depth. Rounding the concept to 22 ft by 22 ft interior gives a garage that works; 20 ft by 20 ft gives one that people back out of sideways.

Limitations and review boundary

• Vehicle dimensions vary widely by model and change between model years.
• Fire separation, opening protection, floor slope, and drainage requirements come from the locally adopted code.
• Setbacks, lot coverage, and driveway access are local planning constraints that may limit the footprint before comfort does.

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