5 Simple Steps To Take The Measurements Of Your Garage Door • Garex

How to

12 February 2021

Whether you want to reduce your heating bill or increase the value and attractiveness of your home, installing a new garage door is always the right decision! Before you start looking around, check out some key things to consider when shopping for a new garage door by reading our article on How to pick the right garage door

However, the starting point for shopping for any big purchase is knowing the parameters of what you are looking for. In the case of a new garage door, take the measurements of the dimensions are the basis upon which the rest can be built, and they entail much more than just the height and width of the rough opening. Measurement errors can be costly: they can complicate the installation of your new door, ramping up fees, and even make the installation impossible.

Garex wants to help you avoid the trial of a bad experience by offering you 5 simple steps to take the measurements of your garage door. By following these instructions, you will have all the information you need from the get-go. Are you ready to start?


When taking the measurements of a garage door, there are a few rules that should be followed to ensure the desired outcome. Here are some guidelines to know before you begin.Firstly, the measurements should always be taken on the finished rough opening of the door, which has a frame and a metal siding. Never take the measurements on the old door. Then, the width and height measurements can be taken at the point where they are the longest.

finished rough garage door opening

Also, note any devices located near the garage door. They could have an impact on the type and size of the opening mechanism required for the proper functioning of the door. Such devices could include a ceiling heater, central vacuum, water heater, or an electrical box, to name a few. Information about the presence of these devices in your garage should be passed along to your installer.

Similarly, irregular wall shapes or structures such as ceiling storage brackets like a mezzanine should be reported to an installer prior to their visit. Regardless of the space configuration available to install the opening mechanism, Garex will manufacture the system best suited to your environment upon request.

Finally, if you have more than one garage door in your garage, we strongly recommend that you take the time to measure each opening individually. Even though the rough openings seem the same at first glance, there are often small differences that will affect their weatherproofing capacity.


Start by fully opening your garage door before take the measurements. We recommend that you ask someone to help you take some of the measurements for the sake of accuracy. Have a tape measure, paper and a pencil on hand, or any other material you normally use for measuring and taking notes.

1. Measure the exact width of the opening

As previously mentioned, measure the width of the opening from the frame or metal cap, and be sure to take the measurements at the widest part of the opening. 

Write down the exact number of feet and inches shown on the tape measure.

2. Measure the exact height of the opening.

Take this measurement from the finished and leveled floor to the inside of the top frame where the measurement is the longest. Jot down the exact number of feet and inches obtained.

Inside your garage, measure the clearance between the side of each opening and the cross wall or, if you have multiple doors side by side, between door openings. Each side of the opening should have a clearance of at least 4″ for a 2″ track, and 6″ for a 3″ track

3. Measure the distance from floor to ceiling, and the headroom

Measure the ceiling clearance from the floor to the lowest point of the ceiling, or to the joists, fluorescents or other structural elements on the ceiling.

measure distance between floor ceiling garage door

Then, obtain the headroom by measuring the space between the top frame of the door opening and the lowest part of the ceiling, joist, or fluorescents.

measure headroom between opening ceiling garage door

If you want to have a garage door opener installed, you will need a minimum headroom of 12”.

4. Measure the side room on either side of the opening.

Inside your garage, measure the clearance between the side of each opening and the cross wall or, if you have multiple doors side by side, between door openings. Each side of the opening should have a clearance of at least 4″ for a 2″ track, and 6″ for a 3″ track.

clearance each side opening garage door

If there is a column or any other type of obstacle between two rough openings, measure the distance from the opening of each door to the obstacle.

measure distance opening each door obstacle garage door

If there is an access door next to your garage door, measure the height of the access door as well as the distance between the rough opening and the wall of the access door.

measure distance rough opening wall access garage door

If your garage has multiple garage door openings side by side, measure the distance between the doors and the distance on each side to the left and right walls. 

measure distance between multiple doors garage door

Clearances that are too narrow, like in these photos, will make installing your new garage door much more complex. It is important to take these side measurements properly and speak to a Garex expert before ordering your new door. The latter will be able to advise you or find viable solutions before you make an investment.

clearances too narrow

5. Measure the backroom.

Measure the unobstructed depth of your garage ceiling. The goal is to find out what the available space for installing of the tracks is.

measure backroom garage door

If your garage has a sloping ceiling, you will have to find the degree of the slope. To do this, establish a horizontal reference point and base your calculations on the height differences from that line. First, measure the distance from the reference line to the ceiling at the location that is the closest to the rough opening, and then between the reference line and the highest point of the ceiling slope. Be sure to take these measurements on the unobstructed depth of your garage ceiling. These measurements will allow you to calculate the degree of slope of the ceiling.

calculate  degree slope ceiling ceiling garage door

Repeat all the steps for each rough opening, if you have multiple doors.


In addition to giving the measurements you have just taken to your garage door installer, a few more things should be provided to them before your installation date.

Tell them what type of material they will be installing the track on: wood, steel or concrete.

Also, let them know if you have a support for the spring.

With all this information in hand, your installer will be able to give you a precise estimate as well as prepare the adequate equipment for a smooth installation.


Now that you have taken all your measurements, we invite you to visit the Garex website for inspiration. You will not only find a wide choice of garage door models for all tastes and budgets, but will also see our customization options for patterns, windows, materials, decorative hardware, colors, and much more. You can even request a free online quote!

Of course, our experts are always available to answer all your questions and to guide you to reputable installers near you.

Visit garexdoors.com now!

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