How to Measure Patio Doors

Updated April 17, 2017

If you are installing a new patio door or replacing an old one, you need to know the patio door measurements. Typically, home improvement stores sell patio doors based on rough opening sizes---the distance between studs and the header and subfloor.

Determine the rough opening of the patio doors by measuring horizontally from stud to stud. If you already have a finished patio door and do not have access to the studs, measure from inside the door frame, and add 1 1/2 to 2 inches for an estimated size of the rough opening.

Measure the height of the opening by measuring from the bottom of the top frame (header) to the top of the subfloor.

Make four measurements---two horizontal measurements on the top and bottom of the opening, and two vertical measurements on each side. This will tell you whether your patio doors are square. Take the smaller of the horizontal and vertical numbers. Write down the measurements on a piece of paper.


Consult a contractor or home improvement specialist if you are unsure about taking measurements of your patio door opening.

Things You'll Need

  • Measuring tape
  • Paper and pencil
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About the Author

Sarah Jae has been writing and editing Web content and consumer health content since 2000. Based in Minnesota, Jae has worked for Mayo Clinic and other local and regional clients. She holds an English and writing degree from University of Wisconsin-Eau Claire.