Most garages are built to have the same size opening to give enough space for a vehicle to comfortably pass through the opening. How to build is not an exact science, and sometimes the opening is a little bit bigger or smaller because there are variations in size; a garage door is measured to get an exact fit for the garage to close easily and fill the full door area.

Depending on where you reside, the typical garage door dimensions are 8 feet wide and 7 feet tall for a single-car garage door or 9 feet wide by 7 feet tall. The double garage door measure 16 feet wide by 7 feet tall, and correct measurements are needed before any garage door is ordered.

If you have a new garage recently built that needs a garage door or plan to replace your old garage door, measuring the exact dimensions of the garage door opener is the first and most important step. Often an assumption that all garage doors are a standard size has led to someone buying a standard garage door and ending up returning it because it is too big or too small. Measure to make sure, here is how:

Table of Contents Show

How are Garage Doors Measured?

Materials

Pen and paper

Tools

Measuring tape
Step ladder

Instructions

Preparation Before Measuring Garage Door

Before measuring a garage door, ensure you have everything you need to complete the task. To have the correct tools and everything ready, follow this checklist:

Measurement must be exact, and the measuring tape must be long enough to measure the longest part of your garage opening in one take. Splitting the measurement into two takes could easily cause an error or miscalculation.
When the garage door opening height is measured, you may be tall and able to stretch and reach that height to take the measurement. For the rest, your best friend in this situation is a step ladder; be sure it is sturdy and safe to stand on.
Draw the garage door opener in a book or on a piece of paper with the width and height so that you can write the exact measurement next to each part it represents on the drawing. The sketch will help you avoid making any mistakes with the garage door measurements.

Step 1: Measuring the Width of the Garage Door Starting Procedure

Measuring the width of the garage door is straightforward. The width of the garage door is the shortest length between the left side and the right side of the garage door. Make sure that the measuring tape is horizontally straight to give you an accurate measurement. Holding it skew will make the distance between the left and right sides longer.

Here are the steps on how to measure the width:

Place the measuring tape's starting point (hook slot) on the ground against the right side of the garage door. Ensure the hook slot touches the wall to give you an exact and accurate measurement.
Holding the case of the measuring tape in your prominent hand, pull the case while using your other hand to grip the blade/tape while holding the hook slot of the tape measure in place.
Ensure that the thumb lock of the measuring tape is released for the blade/tape to slide out.
Pull the case of the measuring tape away from the hook slot until about an arm's length of blade/tape is visible.
Place the exposed blade/tape flat on the ground until you have about three feet of blade/tape down and you can stand holding the case in your hand and enough blade/tape to hold the hook slot.
At this point, it is wise to secure the thumb lock to ensure the hook slot is still in its correct placement.

Step 2: Measuring the Width of the Garage Door Follow Through

Once the measuring tape's hook slot is secured to one side of the garage door, and you have about three feet of blade/tape secured to the ground, you can continue measuring the width of the garage door. Here are the steps to continue measuring the width of the garage door:

With the measuring tape case in your prominent hand and the blade/tape in the other, hold the blade/tape secure and release the thumb lock to continue the measurement. Remember to hold the blade/tape secure with the other hand because a measuring tape has a spring retraction function that will pull the blade/tape back into the case if you do not hold it down.
Once you have a good grip on the blade/tape and release the thumb lock pull the case until you have another arm's length of blade/tape released from the case.
Set the extra arm's length of blade/tape on the ground and secure the thumb lock again.
Continue this procedure until you reach the left side of the garage door, where you can take the measurement.

Step 3: Taking the Width Measurement of the Garage Door

With the blade/tape extending over the full width of the garage door, you are ready to calculate the distance on the blade/tape. Here are the steps to read and calculate the measurement:

At this point, you should have more blade/tape released from the case than the width of the garage door.
Ensure that the blade/tape is straight and covers the shortest distance between the left and right sides of the garage door. If the tape does not run straight, it will measure a longer distance, and your garage door will not fit.
Push the access blade/tape into the bottom corner of the left side of the garage door. If you are doing it correctly, the blade/tape should be at a 90⁰ angle.
Read the measuring tape at its closest point to the wall.
The blade/tape will measure feet written in big numbers, inches in small numbers, and evenly spaced lines to measure portions of an inch.
Calculate the distance on the blade/tape and write it next to the relevant portion of your garage door sketch to remember it.

Step 4: Measuring the Height of the Garage Door Starting Procedure

With the width of the garage door complete, it is time to measure the height. It is like measuring the width, but now you will measure it vertically. To measure the height of the garage door, follow these steps:

Release the thumb lock of the measuring tape and slide out an arm's length of the blade/tape.
Secure the thumb lock of the tape measure again to help you with the hook slot placement.
Place the hook slot of the tape measure in the bottom corner of the garage door.
Secure the tape measure case in your dominant hand and grip the blade/tape with the other.
If you can see that you will not be able to rich the top of the garage door, you will need to take a step ladder and position it so that you can measure the garage door at the top.

Step 5: Measuring the Height of the Garage Door Follow Through

After positioning the hook slot on the bottom corner and securing the thumb lock with an arm's length of blade/tape, you are ready to follow through to the top of the garage door. The continuing procedure is the same whether you are tall enough or using a step ladder. Here are the continuing steps:

While holding the blade/tape and the hook slot secure, release the thumb lock and pull out another arm's length of blade/tape.

There should be enough blade/tape to take the height measurement of the garage door. If it is still not enough, repeat the procedure until you have about a foot more blade/tape than needed to fill the distance.
Ensure that the blade/tape is horizontal and follows the shortest distance from the bottom to the top corner of the garage door. If skewed, it will measure a longer distance, and your garage door will not fit.
Secure the thumb lock and push the blade/tape into the top corner of the garage door.
Take the blade/tape measurement closest to the top of the garage door and write it down next to the relevant position of your garage door sketch.

Step 6: Measuring a Garage Door (Completion)

Once you have measured the width and height of the garage door and written it down, you are complete. These measurements will make it easier for you to order or purchase the correct garage door.

Note that the average single garage door is between eight and nine feet wide and seven feet tall, and a single garage door for a double-parking measures sixteen feet wide and seven feet tall. If your measurements exceed these parameters by a lot, you should either remeasure to ensure your measurements or revisit the size of your garage door opening.

Notes

It is easier if you have assistance to hold the measuring tape hook slot while you measure the other end. And another set of eyes to confirm your measurements are correct is always a good idea.