how to measure the patio door size for purchasing a new one

how to measure the patio door size for purchasing a new one
Tools Needed
1 Utility Knife
2 Crowbar
3 Hammer
4 Cordless Drill
5 Seal
View Full List
Materials Needed
1 Trim
2 Tape Measure
3 Weather Stripping
Total Cost
Find a handyman
Estimated Time
30-45 Minutes
Skill Level: Beginner
The total cost and duration may vary when hiring a handyman!

Project Overview

person measuring a patio door

If you are thinking about replacing a patio door, you will first need to think about the measurements. Buying a new door without measuring the space first is like buying new clothes without trying them on. You can guess if they will fit right but it will just be a guess. You don’t want to get a patio door home just to realize it is too small or too big for the door frame.

Measuring the patio door size so that you can purchase a new one is quite simple and you don’t need to be a pro to get it done. If you do measure the frame and realize they don’t sell that size in stores, custom patio doors can be ordered online. However, just be sure you were careful and exact with the measurements before placing the order.

Step-By-Step Instructions


Removing the Door and Trim

measuring patio door sizes

Before you start to measure the patio door size for purchasing a new one, you must do a few other things first. The seal from around the door is going to need broken and taken down. You will start by inserting the utility knife from one side of the frame, all the way around, to the other side. This will break the seal (this is usually made of silicone and cuts through fairly easy). You will need to cut old paint and silicone seal from the trim on the door. You may find there to be a lot. However, some doors have very minimal. This is the part of the project that may take the most time, especially if there is quite a bit of seal and paint to be removed.

The next step is to take off the door without causing any damage to it. If there are any nails, you will first need to take those out using your hammer. If the trim or door have any screws, you will need to use your cordless drill and the drill bits to get those out. If this step, be careful not to break the trim if you are going to be reusing it. You will want to save that so you can nail or screw it back in later unless you plan to buy new trim when you buy the new door.


Measuring Width & Height

Patio door measurements

After you have taken off the seal and next the door and trim, it is time to start the measuring process. You will want to begin by measuring the width. Start from the left side of the door opening to the right side of the opening. You should take the measurements three times and then write down the smallest size you had gotten. Make sure to measure from one stud to the other using your tape measure. The studs are the 2 by 4 frames on either side of the door. This measuring process is called a rough opening measurement. If there is any weather stripping do not add that to your measurements.

After you have gone through the width measurements three times and wrote the smallest one down, it is time to take the height measurements. With this step, you are again going to take the measurements three times. You will measure from the top of the opening to the bottom of the opening each time. You will then write down the smallest number you came up with during the measurements. Just as with the width, if there is any weather stripping, don’t put that in the measurements.


Measuring Door Jamb

Patio Door Jamb

Now that you know how to measure the width and height of the door opening, you will need to measure the door jamb. With this step, you want to make sure to measure from the trim on the interior to the trim on the exterior. You will take this measurement three times as well. Then, write down the smallest of your three measurements.

If you want to be even more accurate in your measurements, you may want to repeat steps 3 to 5 one more time. You will only need to do the measurements this last time. If you get the same exact measurement as your smallest number that you had previously written down, then you are all set. If the number varies within the numbers you had gotten before but is not bigger than the largest number you had in the step the first time, stick with your smallest number. Now, if the number you get this time is even bigger than the biggest number you got the first time around, you may want to measure it three more times and take the smallest number again or you may want to call a professional door installer.


Getting Ready For A New Door

patio door

After you have done all the measuring and you have the proper measurements, you will want to clean up the debris. You don’t want to go out and purchase a new patio door and possibly new trim if you don’t have the area cleaned up first. You may need to clean up the seal, paint chips or weather stripping if you are replacing that as well. Until you make sure your new door fits, you should keep the old one, just in case that needs to go back on for some reason.

You have measured the opening for your new patio door. Now, you can go to the store to purchase the new door. There are many styles and colors to choose from in patio doors. If you do go to the store and they don’t sell that size, remember that you can order custom sized patio doors online. Just be sure your measurements are completely accurate before placing any online orders. It would be horrible to get a new custom door ordered and not have it fit when was shipped to your home.

Once you get the new patio door, you can get it to your home and install it. The installation time is generally pretty quick as long as all measurements were taken well. It is recommended to have one person holding the door up while the other person screws in the hinges.


If you have been thinking about getting a new patio door but you weren’t sure what the first step is, now you know. You will need to measure the opening of the space where the new door will go. The seal and door will need to be removed so the new one can be put in. If you need to custom order the patio door that is an option as well. This isn’t a large project and doesn’t need to be stressful. It is highly recommended that you also get a new seal and weather stripping for the new door, to make your home more energy efficient. If you want to change the color on the new door to something different than what you have now, you also may want to purchase new trim as well.

How To Measure The Patio Door Size For Purchasing A New One

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