Sometimes you’re working with 5/8 inch fire-rated drywall. That’s thicker. Then your math changes again.
For 5/8 inch drywall on wood studs, use 1-5/8 inch screws. For metal studs? Same length, but self-tapping.
And if you’re screwing into old plaster? Stop. That’s a whole different coffee chat. Just grab a 2-inch screw and hope the plaster doesn’t crumble.
Side note: Always check your local building code. Some places have opinions. Loud ones.
What About Screw Threads?
You might think a screw is a screw. Wrong. Drywall screws have coarse threads for wood, fine threads for metal.
What Is Code For Drywall Thickness - Design Talk
Coarse threads (like a lumberjack’s handshake) grip wood better. Fine threads (like a watchmaker’s tweezers) grip metal better.
For 1/2 inch drywall on wood, get coarse threads. For metal, get fine threads. Mix them up, and you’ll either strip the stud or snap the screw.
And snapping a screw is like hearing a tiny gunshot in a quiet room. Annoying.
