How to Calculate Drywall Needed
Calculating drywall requires measuring your walls and ceiling, subtracting openings like doors and windows, then adding extra for waste and cuts.
Step-by-Step Calculation
- Calculate total wall area: (perimeter x ceiling height)
- Add ceiling area if needed: (length x width)
- Subtract door openings: approximately 21 sq ft each (3' x 7')
- Subtract window openings: approximately 15 sq ft each (3' x 5')
- Add 10-15% for waste and cuts
- Divide by sheet size to get number of sheets
Common Drywall Sheet Sizes
| Size |
Coverage |
Best For |
| 4' x 8' | 32 sq ft | Standard walls, easy handling |
| 4' x 12' | 48 sq ft | Fewer joints, taller walls |
| 4' x 16' | 64 sq ft | Large areas, professional use |
Drywall Thickness Guide
- 1/4": Curved walls, covering existing surfaces
- 3/8": Repairs, double layers
- 1/2": Standard walls and ceilings (most common)
- 5/8": Fire-rated, soundproofing, ceiling applications
Additional Materials Needed
For a complete drywall project, you'll also need:
- Drywall screws: ~1 lb per 500 sq ft
- Joint compound: ~3-4 gallons per 100 sq ft
- Joint tape: ~1 roll per 500 sq ft
- Corner bead: 1 per outside corner
Tips for Drywall Installation
- Hang ceiling drywall before walls
- Stagger joints to increase strength
- Keep screws 3/8" from edges
- Use longer sheets to minimize joints
- Acclimate drywall to room temperature before installing
- Cut pieces slightly smaller than needed for easier fit
Why Add Extra for Waste?
- Cut pieces around outlets and fixtures
- Mistakes and damaged sheets
- Irregular room shapes
- Better to have extra than run short
