To measure for new windows, take the width of the window opening at three points: the top, middle, and bottom. Use the smallest measurement for the final width. For height, measure from the top of the window opening to the bottom of the sill on both sides and in the center. Use the smallest height measurement for an accurate fit and to avoid ordering a window that's too large.

Measure windows by taking width measurements at the top, middle, and bottom of the window frame. For height, measure from the top to the sill in three places and use the smallest measurements. This method ensures the new window fits properly, preventing gaps and air leaks.