Whether you’re renovating your garage to create more space, replacing an old door or building a garage from scratch, you’ll need to measure for your new door. When looking to install a new garage door, you’ll have to measure the opening to determine which size to buy. There are many standard sizes for garage doors as well as custom options available. 

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In this guide, we’ll discuss how to measure for a garage door.

How to Measure for Your New Garage Door


Use the following diagram and instructions to find the measurements of your current garage door or garage door opening. Then, take these dimensions to your local Clopay® garage door dealer or installer to find the garage door that is best for you.

Step 1: Find the Length and Height

The first step to measuring for a garage door is to find the size of the opening. Find the length and height — labeled 1 and 2 on the diagram — of your rough opening to determine what size garage door you need. To find both figures, measure from the two widest points of your garage door opening. The door’s rough opening will be slightly larger than the door you’ll need, and a finished opening should be equal to the size of the door you’ll need.

Step 2: Find the Width of the Sideroom

Your garage door’s new track will fit in the areas to the left and right of the garage door opening. Measure the strip of wall on the left and right margins of your garage door— labeled 3 and 4 on the diagram. You’ll need a minimum of three and three-quarter inches per side to install the track for a standard torsion spring, standard extension springand the EZ-SET® Torsion Spring System. You’ll need at least five and a half inches for the EZ-SET® Extension Spring System.

If you are installing doors for a two-door garage, the center post between both doors will need double the distance. This space should be at least seven and a half inches for a standard extension or torsion spring or the EZ-SET® Torsion Spring System. For the EZ-SET® Extension Spring System, you will need at least 11 inches 

Step 3: Measure the Height of the Headroom

Take the dimensions of the headroom — marked 5 on the diagram. The headroom is the space between the jamb header, or the area above the doorway and the floor joist, or ceiling. If you find an obstruction on your ceiling, such as pipes or light fixtures, you’ll have to adjust your measurement. Find the distance between the top of the door to the bottom of the obstruction. You’ll need 10 inches of headroom for the EZ-SET® Extension Spring System or the standard extension spring. For a standard torsion spring and the EZ-SET® Torsion Spring System, you’ll need at least 12 inches of headroom. For garages with limited headroom, a specialized kit is available. You’ll also need additional headroom to install an automatic garage door opener.

If the height of your garage door stretches out above the opening, start measuring your headroom from the top of the door.

Step 4: Measure the Depth of the Backroom

The backroom is the amount of space you have to fit the garage door when it’s in the upright or open position. Find the dimensions of the area labeled “backroom” — labeled 6 on the drawing. This measurement starts from the opening for your garage door toward the back of the garage. The backroom ends at the first obstruction or when your tape measure reaches the back wall. The amount of backroom you need depends on the height of the garage door you buy. To have the adequate backroom, you’ll need a depth equal to 18 inches plus your garage door height. You may need additional backroom to install an automatic garage door opener, usually about four feet and two inches.

Garage Door Measurement Tips

When following this garage door measuring guide, there are several things you can do to get the most accurate measurement. Following these tips can help you catch any issues the garage door installer should be aware of:

  • Measure to the closest fraction of an inch.
  • Consider taking each measurement from a few different places. When you get the same number several times for each dimension, you can be confident you have an accurate number.
  • Locate the nearest electrical outlet to install the garage door opener.
  • Note any potential obstructions, such as light fixtures, ductwork, pipes or staircases.
  • Examine the door jambs and the header to check their condition. If anything is uneven or unstable, they may need replacement.
  • Check if the floor is level. An uneven floor might mean your previous door was a custom fit.

Common Garage Door Sizes

Generally, there are three different garage door sizes to choose form:

1. Single Garage Doors

Single garage doors come in three standard sizes: 10-by-7 feet, 9-by-7 feet and 8-by-7 feet. Standard 10 and nine-foot garage doors are suitable for standard homes and cars. For larger cars such as RVs and Bobtails, a double garage door is likely a better option. Eight-foot garages aren’t usually installed in new houses today but are readily available for older homes that have this size opening. Garages with doors smaller than eight feet can be used to house golf carts, riding lawnmowers and small tractors, but will require a custom fitting.

2. Double Garage Doors

Large vehicles, work trucks, multi-car garages and garages with lots of storage space are best off with double garage doors. The standard sizes for double garage doors are 16-by-7 feet, 14-by-7 feet, and 12-by-7 feet. Clopay® garage doors also come in 15-foot, 15-foot 6 inches, and 18-foot door lengths. 

3. Custom Garage Doors

After measuring your garage door, you may realize your opening is not a standard size. Some Clopay® models can be custom ordered in length increments of two inches and height increments of three inches. If you are building a custom size garage, renovating your existing garage, or looking to fit a garage door opening with non-standard dimensions, you will be best off with a custom-fitted garage door. An uneven or sloped garage floor might also be fitted with a custom-sized garage door.

Contact Us Today for Garage Door Measurements

Contact Us Today for Garage Door Measurements

Now that you know how to measure a garage door, the next step is to find the garage door that fits your space requirements and complements your home’s exterior. If you’re ready to pick out your favorite, Halo Overhead Doors has a large selection of door styles to choose from.

Do you need a second opinion on your garage door measurement? The garage door installation professionals at Halo Overhead Doors can help you find the correct dimensions for your new garage door. As a member of the International Door Association and the only Clopay® Master Authorized Dealer in Houston, you can be sure you’re getting a high-quality installation. Each of our installers has a minimum of five years of experience, so you get expert service every time. At Halo Overhead Doors, we help you protect your home with tough doors and loyal service. 

Are you interested in fitting your home with new garage doors? Contact us today, and we can measure and install the perfect door for your garage.

Contact Us Today