How this estimate works
The calculator applies: ceil((wallArea + ceilingArea) x (1 + waste/100) / sheetArea). Keep measurements in one unit system and round up when suppliers sell whole units.
Limitations
Sheet size, openings, fire-rated layers, access panels, and local code change the count.
Source to check
Read the authoritative guidance for drywall calculator
Frequently asked question
Do I subtract doors? Only if you measure net wall area; keeping a cutting allowance is usually safer.