How to Measure a Window Rough Opening for Replacement #3088352 (License: Personal Use)

This instructional diagram illustrates the standard method for measuring a window’s rough opening during replacement projects: dimension A represents the horizontal width measured at the bottom of the opening, while dimension B indicates the vertical height measured along the side jamb. Accurate measurements are critical to ordering correctly sized replacement windows and avoiding gaps or fit issues during installation.

Used on home improvement, contractor, or window manufacturer websites to guide DIYers and professionals in preparing for window replacement; matches user intent to learn proper measurement techniques before purchasing.