Garage Door System GuideGarage doors come in a small set of standard sizes, and getting the measurements right matters before you order. Clopay identifies 8 feet by 7 feet and 9 feet by 7 feet as the two most common single-car sizes and 16 feet by 7 feet as the classic double-car size. The sections below cover those standard dimensions and the headroom, backroom, and sideroom you need to measure, each tied to a dated source.
Standard Single-Car Garage Door Sizes
Single-car doors cluster around a handful of dimensions. Clopay names 8 feet wide by 7 feet high and 9 feet wide by 7 feet high as the two most common single-car sizes, and notes the 9-foot width is popular because it gives just a bit more clearance.
Precision Garage Door's size chart broadens the set slightly, listing 8 by 7, 8 by 8, 9 by 7, and 9 by 8 feet as standard single-car dimensions. The extra options reflect the choice between a 7-foot and an 8-foot height on the same widths.
Height is the variable most homeowners overlook. A 7-foot height is the long-standing default, while the 8-foot height appears on the same 8-foot and 9-foot widths for taller vehicles or added clearance.
Standard Double-Car Garage Door Sizes
Double-car doors are built to span two vehicles on a single panel. Clopay calls 16 feet wide by 7 feet high the classic measurement and the baseline for double doors in residential garages.
Precision Garage Door confirms 16 by 7 feet as the most common double-car size and reports that double-door widths range between 12 feet and 20 feet. That range covers narrower two-car openings and wider bays that fit larger vehicles side by side.
As with single doors, the 7-foot height carries over as the default, and the width is where most of the variation lives.
How to Measure Headroom and Backroom
Headroom is the space above the door opening needed for the tracks and springs. Clopay's track guide states that for a 2-inch track the standard radius is typically 12 or 15 inches, requiring at least 12 inches of headroom for a 12-inch radius and 14.25 inches for a 15-inch radius.
Backroom is the depth into the garage the door needs to slide open. Clopay's standard radius track calls for backroom equal to the door height plus 16 inches, so a 7-foot door needs about 100 inches of clear depth.
When headroom is tight, low-headroom track changes the math. Clopay notes a front-mount low-headroom track typically needs 9 inches of headroom and a rear-mount version needs only 4.5 inches, though the rear-mount trades that off against backroom of door height plus 30 inches.
How to Measure Sideroom and Rough Opening
Sideroom is the wall space on each side of the opening where the vertical track mounts. Precision Garage Door's size chart states you need at least 3.75 inches on each side for the vertical tracks.
Headroom above the opening also needs a minimum. Precision Garage Door lists a minimum headroom of at least 6 inches above the door and 14 to 18 inches of ceiling clearance to fit the opener system, and it advises allowing at least 2 feet between parked vehicles.
The rough opening itself is straightforward. The opening should match the nominal door size, so a 16-by-7-foot door fits a 16-by-7-foot framed opening, with the clearances above measured out from there.
High-Lift Track for Tall Garages
Garages with high ceilings can use high-lift track to raise the open door higher and free up overhead space. Clopay's track guide states a high-lift setup needs the high lift dimension plus at least 9.5 inches of headroom above the door.
For backroom, Clopay notes that standard backroom of door height plus 18 inches usually applies to a high-lift configuration. That keeps the depth requirement close to a standard install even as the vertical clearance increases.
High-lift is the option to raise when you want overhead storage or a lift installed near the ceiling, provided the wall above the opening has the headroom the track requires.