Drywall Calculator
To calculate drywall, find the total wall area (perimeter × height) plus the ceiling if covering it, add 10% for waste, and divide by the sheet size. A 14×12 ft room with 8 ft walls and a ceiling needs about 21 sheets of 4×8 drywall, costing roughly $880–$2,050 hung and finished.
- 4×8 sheet
- 32 ft²
- Compound
- ~0.05 lb/ft²
- Screws
- ~1 per ft²
Your measurements
Enter your measurements
Fill in the fields to see your estimate.
The formula
Sheets = (Wall area + ceiling area) × (1 + waste %) ÷ sheet areaHow to calculate it manually
- 1
Calculate wall area
Add all wall lengths (perimeter) and multiply by the wall height.
- 2
Add the ceiling
If drywalling the ceiling, add length × width.
- 3
Add 10% waste
Account for cuts around windows, doors, and outlets.
- 4
Divide by sheet size
A 4×8 sheet covers 32 ft²; larger sheets mean fewer seams.
Example calculation
A 14×12 ft room, 8 ft walls + ceiling: walls 2×(14+12)×8 = 416 ft² + ceiling 168 ft² = 584 × 1.10 ≈ 642 ÷ 32 ≈ 21 sheets.
Drywall sheet size guide
Larger sheets mean fewer seams to tape and finish, but are heavier to handle.
| Sheet size | Coverage | Best for |
|---|---|---|
| 4 × 8 ft | 32 ft² | Tight spaces, DIY |
| 4 × 10 ft | 40 ft² | Standard walls |
| 4 × 12 ft | 48 ft² | Long walls, fewer seams |
Common drywall estimating mistakes
Forgetting the ceiling
If you're drywalling the ceiling too, add its area (length × width) — it's easy to leave out and come up short.
No waste allowance
Cutouts for windows, doors, and outlets create scrap. Add at least 10% so you're not short a sheet.
Underestimating finishing supplies
Joint compound, tape, and screws add up. Budget about one 5-gallon bucket of mud per 12 sheets.
Choosing the wrong thickness
Use 5/8 inch for ceilings and fire-rated walls; 1/2 inch is standard elsewhere. Moisture-prone areas need water-resistant board.
Frequently asked questions
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