How it works
Wall area is the room perimeter times ceiling height, plus ceiling area (length × width). Sheets needed are that area, increased by your waste percentage, divided by sheet area (32 sq ft for a 4×8 sheet), rounded up to whole sheets.
Frequently asked questions
Should I deduct doors and windows?
You can, but most estimators do not — offcuts around openings still use material, and a few spare sheets are cheaper than a second trip.
What about joint compound and screws?
This calculator counts sheets only. Compound, tape, and screws depend on your finishing level and are sold separately.