: Measure the height, width, and thickness of the opening. Subtract approximately 1/8 inch from the width and height to allow for the frame's expansion and contraction.

: For wood frames, sand the grooves and apply a sealer or linseed oil to prevent the new putty from drying out too quickly.

: Large retailers like The Home Depot and Lowe's sell glass sheets and many locations will cut them to your specific dimensions in-store.

: If you have modern double-pane windows, you must replace the entire sealed unit rather than just one pane to maintain insulation properties.

: Wear heavy-duty gloves and eye protection to remove broken shards. Use a heat gun and putty knife to soften and scrape away old glazing compound or sealant.