Drywall Calculator
A 12×14 ft room with 9 ft ceilings needs 14 sheets (4×8 ft) for walls plus 6 sheets for the ceiling — 21 sheets total. Materials: $280-500.
Drywall Calculator
Enter your project dimensions for instant results.
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How to Calculate Drywall
The formula calculates total area and divides by sheet size:
wall_area = (2 × (length + width) × height) - (doors × 21) - (windows × 15)
ceiling_area = length × width
sheets_4x8 = Math.ceil((wall_area + ceiling_area) × 1.10 / 32)
| Size | Area | Best for | Weight (1/2″) |
|---|---|---|---|
| 4×8 ft | 32 sq ft | Standard rooms, DIY | 57 lbs |
| 4×10 ft | 40 sq ft | 9 ft ceilings | 71 lbs |
| 4×12 ft | 48 sq ft | 10 ft ceilings, fewer seams | 85 lbs |
| Thickness | Use |
|---|---|
| 1/4″ | Curved walls, overlay on old plaster |
| 3/8″ | Overlay, budget non-load walls |
| 1/2″ | Standard walls (most common) |
| 5/8″ | Ceilings (sag-resistant), fire-rated walls |
| 5/8″ Type X | Fire-rated (garage, furnace room, code-required) |
| Material | Quantity | Cost |
|---|---|---|
| 1/2″ drywall sheets | 32 (4×8) | $320-420 |
| Joint compound (pre-mixed) | 7-8 gallons | $70-100 |
| Paper tape | 3 rolls (250 ft) | $12-18 |
| Drywall screws (1-1/4″) | 3 lbs (~700) | $15-25 |
| Corner bead (metal) | Per corners | $2-4 each |
Common Mistakes:
- Using 1/2" on ceilings with 24" joist spacing — it sags; use 5/8" for ceilings
- Not buying enough joint compound — you'll need 3 coats minimum and the bucket runs out faster than expected
- Hanging drywall vertically instead of horizontally — horizontal installation creates fewer lineal feet of seam to tape
Frequently Asked Questions
How many sheets of drywall do I need for a 12x12 room?
For walls only with 8 ft ceilings: about 11 sheets (4×8 ft) after subtracting one door and one window with 10% waste. Add the ceiling: 6 more sheets. Total: 17 sheets. At $10-13 per sheet, materials cost $170-220 for drywall alone.
How much does it cost to drywall a room?
DIY materials for a 12×14 room: $280-500 (drywall, compound, tape, screws). Professional installation: $1.50-3.00 per square foot, meaning the same room costs $900-1,800 installed and finished. Most of the pro cost is taping and finishing labor, not materials.
Should I use 4x8 or 4x12 drywall sheets?
Use 4×12 for 9-10 ft ceilings — one sheet covers wall height horizontally, eliminating the middle horizontal seam. Use 4×8 for standard 8 ft ceilings or where access is tight (narrow hallways, staircases). Longer sheets are harder to handle — you'll need a helper.
How much joint compound do I need?
About 0.067 gallons (0.27 quarts) per square foot of drywall for three coats. A 12×14 room with ceiling needs roughly 5 gallons of pre-mixed compound. Buy an extra gallon — running short mid-coat means a visible line where you stopped.
What type of drywall do I need for a bathroom?
Use moisture-resistant (green board or purple board) drywall for bathroom walls outside the shower/tub area. Inside the shower enclosure, use cement backer board (Durock, HardieBacker), not drywall — even moisture-resistant drywall fails in direct water contact.
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