Wear safety glasses, a dust mask, gloves, and hearing protection
Measure and mark the cut line with a pencil or chalk
Place the cement board on a stable, flat surface
Score the cut line with a carbide-tipped scoring knife
Snap the board along the scored line
Cut the back side with a utility knife if needed
Use a jigsaw with a carbide or diamond blade for curves or openings
Use a circular saw with a fiber-cement blade for long straight cuts
Cut outdoors or in a well-ventilated area to reduce dust
Support the board close to the cut to prevent breakage
Smooth rough edges with a rasp or sandpaper
Clean up dust with a vacuum or damp cloth