How Do You Measure a Garage Door Opening?

How do you measure the rough opening of a garage door? Here are some tips to consider before you start:
- Provide measurements to the closest fraction of an inch.
- If you measure for a new garage door opening, check that the area has access to electricity. You will need power for your automatic garage door opener.
- Inspect your current garage door. Write down any irregularities or signs of damage you see on the tracks, springs or seals.
- Make sure the tape measure is level from one side to the other.
- If your current door is a custom fit, you may need to order a new custom garage door instead of one at a standard size.
- Note any ductwork or pipes that may obstruct the pathway of your garage door track.
If your home has more than one garage, you need to measure each garage door rough opening. Even if they look like the same size, you want to have an accurate measurement of each door.
Here are the steps for measuring a garage door:
1. Measure the Width of the Door
The width of your garage door includes the distance between the left and right sides of the finished opening. Use a tape measure to measure at the door’s widest point in feet and inches. For an accurate size, record the distance from more than one spot on the garage.
You should also note if there are any irregularities from one side to the other, like an unleveled side. Use a level to determine if your wall is even or not. If you have one unleveled side, you can change the size of the garage door seal.
2. Measure the Height of the Door
The height is the distance between the floor and the ceiling of the finished opening. Measure at the door’s highest point in feet and inches. Order the exact size door you need instead of allowing space for the door jamb or the seal.
Write down if you notice any irregularities in the height of the door, like an unleveled floor. Your garage door company should know about defects, so they can make adjustments as needed. If your flooring is not level, you can change the size of the garage door seal.
3. Measure the Side Room
Using your tape measure, measure the headroom. This distance consists of the top of the opening to the nearest obstruction. If you have ceiling storage in your garage, record the distance from the opening to the shelf. If you don’t have any blockage, the headroom is the opening to the ceiling.
You need three to four inches on either side of the door to allow for the vertical track and the extension springs. The inside of the garage door should have a wood jamb. Don’t include this frame in your measurements.
4. Measure the Headroom
Using your tape measure, measure the headroom. This distance consists of the top of the opening to the nearest obstruction. If you have ceiling storage in your garage, measure from the opening to the shelf. If you don’t have any blockage, the headroom is the opening to the ceiling.
Make sure the distance between the opening and the ceiling is at least ten inches to follow garage door header requirements. You need to make sure you have enough space for the torsion spring and garage door opener. The type of garage door you choose will determine how much space you need above the opening. Thicker garage doors, such as wooden garage doors, need more space above the opening for clearance.
5. Measure the Backroom
The backroom is the distance between the garage door and the rear wall of the garage. You need to know the length of the backroom, so you know how much space you have for the garage door to open into the garage. Make a note of any irregularities in the ceiling or walls.
The garage door should have plenty of room to open completely. You need to allow 18 inches of free space on top of the measurement of your garage door. If you have a smaller garage, you will need a garage door that fits in this tiny space.