Drywall Calculator
Enter your room dimensions to get a sheet count, waste-adjusted total, and material cost estimate. Supports both 4×8 and 4×12 sheets.
How to Calculate Drywall for a Room
The basic process is to find your total wall area, subtract openings, then divide by the sheet coverage and round up.
- Wall area = Perimeter × Ceiling height = 2 × (Length + Width) × Height
- Subtract openings — standard door ≈ 21 sq ft, standard window ≈ 15 sq ft
- Add ceiling area (if drywalling ceiling) = Length × Width
- Add waste factor — 10–20% depending on room complexity
- Sheets needed = Total sq ft ÷ sq ft per sheet, rounded up to the nearest whole sheet
Sheet sizes
The most common drywall sheet is 4×8 ft (32 sq ft). For rooms with 9–10 ft ceilings, 4×12 ft sheets (48 sq ft) reduce the number of horizontal joints. Longer sheets are heavier and harder to handle solo, but finishers often prefer them.
Drywall takeoffs always look simple until you're standing in the room. Corners, archways, outlets, and cutouts eat sheets fast. Even in a plain rectangular room, I add 10% minimum — and 15–20% for any room with a closet, knee wall, or cathedral ceiling. You're buying sheets anyway; running short mid-job means a second trip and mis-matched lots from different manufacturing runs.
Drywall Cost Estimates (2026)
Prices below are for standard 1/2" drywall at big-box retailers. Specialty board (fire-rated, moisture-resistant, soundproof) costs more.
| Type | Sheet cost (4×8) | Use case |
|---|---|---|
| Standard 1/2" drywall | $13–$18 / sheet | Interior walls and ceilings |
| 5/8" Type X (fire-rated) | $18–$24 / sheet | Garage walls, fire separation |
| Moisture-resistant (green board) | $16–$22 / sheet | Bathrooms, laundry rooms |
| Cement board (Durock) | $22–$32 / sheet | Tile backer, showers |
| Soundproof drywall | $40–$60 / sheet | Home theaters, shared walls |
Labor costs
If you're hiring it out, hanging and finishing drywall typically runs $1.50–$3.50 per square foot for labor, depending on ceiling height, finish level (Level 4 vs. Level 5), and your region. Taping and finishing alone is roughly $0.75–$1.25/sq ft.
For bathrooms and areas near water, never use standard drywall — even if you're tiling over it. Tile doesn't fully waterproof the substrate. Moisture-resistant drywall or cement board behind tile is a small upcharge now versus a mold remediation bill later. I've seen it go wrong more than once.
Frequently Asked Questions
How many sheets of drywall do I need for a 12×12 room?
A 12×12 room with 8-foot ceilings has about 384 sq ft of wall area. Subtract 1 door (21 sq ft) and 1 window (15 sq ft) → 348 sq ft. Add 10% waste → 383 sq ft. At 32 sq ft per sheet, that's roughly 12 sheets for walls. Add the ceiling (144 sq ft ÷ 32 = 5 sheets) for 17 sheets total.
How thick should drywall be?
1/2 inch is the standard for interior walls and ceilings. Use 5/8 inch for garages (fire code), extra sound isolation, or ceilings prone to sagging. 3/8 inch is used for curved walls or repair patches.
Should I drywall the ceiling or walls first?
Always ceiling first. The wall sheets then butt up under the ceiling sheets, supporting them and creating a tighter joint. Doing walls first leaves the ceiling edges unsupported and harder to finish cleanly.