Paint Calculator
The next step after the tape and mud — wall paint quantity.
Walls & ceilings
How many sheets of drywall do I need?
Enter the room length, width and ceiling height and the drywall calculator counts the 4 × 8 ft sheets for walls and ceiling, with doors and windows deducted. A 10 × 10 ft bedroom with 8 ft ceilings needs about 9–10 sheets for the walls and 4 more sheets if you also sheet the ceiling.
Walls and ceiling are estimated separately and openings are deducted automatically, so the count stays realistic for anything from a small closet to a full basement build-out. Switch between 4 × 8, 4 × 10 and 4 × 12 ft boards, add the standard 10% cutting waste, and use the result to order drywall boards, joint compound and screws in a single trip.
Frequently asked questions
How many sheets of drywall for a 10×10 room?
Walls only: about 10 sheets of 4×8 drywall. Walls plus ceiling: about 14 sheets. That already includes a 10% cutting allowance for a standard door and window.
How many sq ft does one sheet of 4×8 drywall cover?
A full 4 × 8 ft sheet covers 32 sq ft before cutting. After the typical 10% waste allowance, plan on about 28–29 net sq ft per sheet.
What thickness drywall should I use?
1/2 inch drywall is standard for walls. Use 5/8 inch (Type X, fire-rated) on ceilings with 24-inch joist spacing, in attached garages, and anywhere fire codes require it.
Should I sheet the ceiling before or after the walls?
Ceiling first. It's easier to wedge ceiling panels into place before wall sheets are up, and the ceiling edges will be covered by the top of the wall sheets — a cleaner, straighter seam to tape.
How many sheets of drywall for a 12×12 room with 8 ft ceilings?
About 12–13 sheets of 4×8 drywall for the walls and 4–5 more if you also sheet the ceiling — roughly 17 total with a standard door and window and a 10% cutting allowance. Type the room into the calculator for your exact openings.
Can I estimate several rooms of different sizes at once?
Yes. Add each space as a separate region — name it "bedroom", "hall" or "garage" — set its own doors, windows and ceiling option, and the drywall calculator rolls every area into one combined sheet total for the whole project.
Drywall Calculator
Imperial
ft
ft
ft
× 21 sq ft
× 15 sq ft
Sheet the ceiling too?
Cutting waste
Enter your room size to see the result.
–
sheets
Use 5/8 in drywall for ceilings on 24 in joists — count stays the same, weight differs.
How it works
How to use this drywall calculator
1Measure the room
Length, width and ceiling height in feet. The tool works out the whole wall area from the perimeter and subtracts door and window openings.
- Add 2 ft to the wall height for vaulted sections, or measure each wall.
- For L-shaped rooms, run it twice and add the sheet counts.
- Garages and basements usually have exposed ceiling joists — select "walls only".
2Pick the sheet length
4 × 8 ft sheets are the standard. Taller 9-ft ceilings are faster with 4 × 12 sheets that span floor-to-ceiling without a horizontal joint.
- 4×8 (32 sq ft): standard rooms, easy to carry.
- 4×10 (40 sq ft): 9-ft and 10-ft ceilings.
- 4×12 (48 sq ft): fewer joints, needs two people.
3Read the sheet count
The result includes a 10% cutting allowance by default. Buy one or two extra sheets if the room has lots of angles, niches or a window wall — offcuts from big sheets rarely patch each other when the layout is tight.
The math
Drywall quantity formula
Wall area = 2 × (length + width) × wall height − (doors × 21) − (windows × 15) (+ ceiling = length × width, when selected)
Sheets needed = wall area × (1 + waste) ÷ sheet square footage (rounded up)
Worked example — 10 × 10 ft room, 8 ft walls, 1 door, 1 window, ceiling included, 4×8 sheets, 10% waste:
Walls: 320 − 21 − 15 = 284; + ceiling 100 = 384 sq ft; × 1.1 = 422 ÷ 32 = 13.2 → 14 sheets.
Walls: 320 − 21 − 15 = 284; + ceiling 100 = 384 sq ft; × 1.1 = 422 ÷ 32 = 13.2 → 14 sheets.
Sheet guide
Drywall sizes & when to use them
| Sheet size | Area | Best for |
|---|---|---|
| 4 × 8 ft | 32 sq ft | Standard 8-ft ceilings, DIY |
| 4 × 10 ft | 40 sq ft | 9-ft and 10-ft ceilings |
| 4 × 12 ft | 48 sq ft | 12-ft walls, fewer seams |
| 4 × 14 ft | 56 sq ft | Stairwells & tall foyers |
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