Wear safety glasses, cut-resistant gloves, and long sleeves
Clean the mirror surface thoroughly
Measure and mark the cut line with a glass marker or grease pencil
Place the mirror on a flat, stable surface with a soft backing
Use a straightedge or ruler to guide the cut
Apply a single, firm score along the marked line with a glass cutter
Keep steady pressure and do not score the same line multiple times
Position the scored line at the edge of the work surface
Snap the mirror cleanly along the score line with gentle downward pressure
Use running pliers if needed for a controlled break
Smooth sharp edges with a glass file or fine-grit sanding stone
Dispose of broken pieces carefully in a wrapped container
Use a wet sponge or tape over the cut line to reduce chipping if needed