Measure the height of the rough door frame opening from the bottom to the top with a tape measure. Measure the width of the rough door frame opening along the bottom of the door opening. These are the rough opening measurements. You will need to use these measurements to get the correct size for the replacement door.
Open up the hinge-side door frame paper template that was included with the replacement door. Tape the paper template to the hinge side of the door frame with masking tape.
Center the scratch awl point in the center of each hinge mounting hole marking on the paper template. Press the awl through the paper template and punch the wood door frame enough to mark the wood.
Remove the hinge-side door frame paper template. Drill a 1/2-inch deep hole at each punch mark on the hinge side of the door frame that you made in Step 3 using a drill equipped with a self-centering pilot hole bit to dimple the frame for the hinge screws.