Calculate how many drywall sheets you need for a wall or ceiling, based on area, standard sheet size and waste.
The calculator adds waste to the area, then divides by the area of a single sheet:
A common drywall sheet size is 1200 × 2400 mm, giving 2.88 m² per sheet. If you're covering walls with many corners, doors or windows, it can pay off to increase the waste percentage somewhat.
For large openings (big window walls, double doors) it can be worth it. For regular doors and windows it's often simpler to just plan for a bit extra waste, since cut-off scraps often can't be reused elsewhere.
Yes, fire-separation walls often require two layers of drywall. Check the requirements in your local building code or with a professional, and double the sheet count if needed.