To measure windows for replacement, take the width of the window opening at 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 at three points. Again, use the smallest measurement for an accurate fit and to ensure the replacement window fits properly.

Replacement windows are measured by taking the width and height of the window opening at multiple points and using the smallest measurement. This ensures the replacement window fits snugly, preventing gaps, drafts, and air leaks.