To measure for replacement vinyl windows, measure 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 measurement for an accurate fit.

Measure vinyl replacement windows by taking width measurements at the top, middle, and bottom of the opening. Use the smallest measurement. For height, measure from top to sill in three places and use the smallest number for a precise fit.