wrote:
I need to replace the window on my vinyl sided house. I took the window
out temporarily and measures the square of the window that fits into the
rough opening. It measured 31 9/16 wide x 71 9/16 tall. I cant find a
window locally anywhere this size.

Is this an odd size and is my only option having one custom ordered?

Others have mentioned that you need to measure the Rough Opening, but no
one mentioned the proper way to do that.

You should measure the width and height of the RO in at least 3 different
spots - usually left, right middle for height and top, bottom, middle for
width. You then use the smallest of the height and width measurements when
you order your window.

RO aren't always perfect. If you take one measurement and it ends up being
the largest one, the new window won't fit. Take at least 3 measurements
while visually inspecting the RO for anything that might be an issue.

I bought my windows through a local Norandex-Reynolds dealer. They don't
stock windows, they place individual customer orders based on the RO sizes
submitted by the customer. IOW, each window is custom made and given an
individual serial number for ease of replacement if there is ever a
problem. I had a sash go bad a few years after I installed the windows. I
called the company, gave them the serial number and about a week later I
had my replacement sash, no questions asked.