Measuring for Outlet Cutouts
The goal is to transfer the box location from the wall to the drywall sheet. You need both horizontal and vertical measurements from reference points.
The Chalk Method
An alternative to measuring is transferring the box outline directly to the drywall.
Rub chalk or lipstick on the edges of the electrical boxes. Position your drywall sheet and press it against the boxes. The chalk transfers to the back of the drywall, marking the exact box location.
Cut from the back of the sheet, following the chalk lines. Flip and install normally.
This method is faster when you have multiple boxes in one sheet. It's also more accurate because you're getting the actual position rather than relying on measurements that can have compounding errors.
The downside is you need to position a full sheet to mark it, which can be awkward on walls and almost impossible on ceilings without help.
Cutting Techniques
Several tools work for outlet cutouts. Choose based on what you have and your comfort level.
Box Depth Considerations
According to the International Code Council guidelines, electrical boxes should end up flush with the finished drywall face. If the box is too deep, switches and outlets won't seat properly. If it's too shallow, the drywall won't sit flat.
Check box depth before installing drywall. The box front edge should protrude from the stud face by the thickness of the drywall you're installing. For 1/2-inch drywall, the box should stick out 1/2 inch.
If boxes are set wrong, you can adjust them. Most residential boxes can be pried forward slightly or hammered back. Some have adjustable depths built in.
Box extenders are available if a box is too deep after drywall is installed. They're an ugly solution to a problem that's easier to fix before drywalling.
Special Cases
Multiple Boxes in One Sheet
Common in kitchens and living rooms. Measure each box carefully and transfer all cutouts before cutting anything. Errors compound when you're making multiple cuts, so double-check everything.
The chalk method really shines here. One marking pass gets all the boxes.
Boxes Near Sheet Edges
When a box falls close to a drywall seam, you have choices. You can cut through two sheets, making half the cutout on each. Or you can adjust your sheet layout to put the box entirely on one sheet.
I try to keep boxes on one sheet when possible. Cutouts that span seams look messier and are harder to get right.
Working Around Junction Boxes
Ceiling junction boxes for lights follow the same principles. Measure from walls or reference points, transfer to the sheet, cut oversized. The canopy of the light fixture covers significant gaps.
Recessed light cans are trickier because the can clips grab the drywall edge. You need more precision there. Templates for common can sizes help.
Common Mistakes
Mistakes I've made so you don't have to:
Measuring from different references. If you measure the horizontal from the corner but the vertical from an already-hung sheet edge, your reference points don't match. Pick consistent references.
Forgetting which side is which. The face of the drywall versus the back. Measurements transferred wrong because I was thinking about the sheet upside down. Mark the face clearly before measuring.
Cutting too tight. Trying for precision that cover plates make unnecessary. Cut loose, fit easy, cover plate hides everything.
Not checking measurements. My first blown cutout happened because I wrote down one measurement wrong and didn't verify before cutting. Always double-check.