We are going to hire somebody to replace our sliding glass patio door. Its a standard sliding glass patio door, similar looking to this:

enter image description here

I am going to buy the replacement door at auction, but first I need to know exactly what size door I need. I searched how to measure this online, but there appears to be contradictory advice on what the proper way to measure a patio door is.

Is there a proper way to measure the size door I need without removing the existing door first? Please include pictures if possible and define your terms if they are not terms a layman could understand.

  • Why don't you let the contractor measure for the door, and take him/her to the auction so you get the correct sized door? Experiences with homeowners buying things like this, is the item is usually wrong.
    – Gunner
    Commented Nov 26, 2012 at 3:52
  • 2
    @Gunner Its impractical since hes so far away. The home buyers are likely usually wrong because the guidance that exist online to do this is incomplete at best. I posted here in the hopes that somebody that knows what they are talking about could fill in that gap, not just tell me to get a professional to measure it.
    – n00b
    Commented Nov 27, 2012 at 1:32

3 Answers 3


What you need to know is the rough opening size. This is the dimensions between the vertical studs and the horizontal dimension from the floor to the bottom of the header. You may have to remove some trim to see these components. If you are going to have a contractor install the new door, have that person give you the proper measurements for the replacement door. You can always go slightly smaller, but not larger.

  • I agree with Shirlock and Gunner, get the contractor to do the measurements. Don't buy a door yourself at auction, you are asking for lots of headache!
    – GdD
    Commented Nov 26, 2012 at 11:08
  • 1
    Thank you Shirlock. Following your advice I simply had to remove the trim, and then could see the wooden frame and measure appropriately. This was something I could do quite easily, and would say any homeowner could do. If anyone else wants to try it just be sure to score the trim before you do, to minimize paint peeling off with the trim.
    – n00b
    Commented Feb 20, 2013 at 21:01

Your rough opening is either 60" by 80" or 72" by 80 ". The manufacture makes the door a half inch smaller both horizontal and vertical to fit the opening. So a 60 by 80 door is actually 59.5 x 79.5. And it's not rocket science to put it in. You don't need a high school dropout claiming to be a professional to install it. All you need is a level and shims. Make sure it is square and plumb and you're good to go.

  • You should not blindly claim a persons portal size. Mine did not fit your description Commented Jun 24, 2019 at 12:46

Most 6'8 doors are 79 1/2 tall by 59 1/2 wide or 71 1/2 wide.

  • 2
    This doesn't answer the question.
    – Tester101
    Commented Oct 6, 2014 at 11:03

Not the answer you're looking for? Browse other questions tagged or ask your own question.