Guide · Drywall

How Many Sheets of Drywall Do I Need for a 12×12 Room?

17 sheets of standard 4×8 drywall: 12 for the walls and 5 for the ceiling, assuming 8-foot ceilings. Add a 10% cutting-waste allowance and order 19. If you can handle 12-foot sheets, you only need 11 — 8 for the walls and 3 for the ceiling — with far fewer joints to tape.

Here’s the full math, a chart for other room sizes, and notes on thickness, doors and windows, and screws and mud. For an exact count for your room, use our free drywall material calculator — it handles walls, ceilings, sheet size, and waste in one pass.

The math, step by step

1. Wall area. The room’s perimeter is 12+12+12+12 = 48 ft; times 8-ft ceilings = 384 ft².
2. Ceiling. 12 × 12 = 144 ft².
3. Total and divide. 528 ft² total. One 4×8 sheet covers 32 ft²: 528 ÷ 32 = 16.5, round up to 17 sheets.
4. Split it. Walls: 384 ÷ 32 = 12 sheets exactly. Ceiling: 144 ÷ 32 = 4.5, round up to 5 sheets.
5. Add waste. 17 × 1.10 = 18.7 — order 19.

The 12-foot sheet trick

Hang the walls horizontally with 4×12 sheets and each 12-ft wall takes exactly two sheets — no butt joints at all. That’s 8 sheets for all four walls, plus 3 for the ceiling (each 4×12 covers a 4-ft strip of the 12-ft ceiling). Total: 11 sheets, and dramatically less taping and mudding. The catch: 12-ft sheets are heavy and awkward in stairwells and hallways, and not every store stocks them — call ahead before you plan around them.

Drywall sheets for common room sizes

4×8 sheets, 8-ft ceilings. Walls and ceiling are rounded up separately, since wall offcuts rarely tile a ceiling cleanly.

Skipping the ceiling? Garages, basements, and covered patios often get walls only. For a 12×12 room that’s 12 sheets of 4×8 before waste — 14 with the 10% allowance — and the “walls” column in the chart works for any room size.

Should you subtract doors and windows?

For ordering, usually not. A standard door is about 21 ft² and a window about 15 ft² — one door plus two windows removes 51 ft², or roughly 1.6 sheets. That’s smaller than the 10% waste allowance on a 12×12 room (about 1.7 sheets), so the offcuts roughly cancel out and you’ll want the spare material anyway. Subtract only genuinely large openings — sliding glass doors, big picture windows, open cased entries — and even then, keep the waste factor.

What thickness of drywall?

½-inch is the standard for walls. Ceilings usually get ½-inch too, but ⅝-inch resists sag on 24-inch joist spacing and is required by fire code in garages and some multifamily assemblies. ¼-inch is an overlay product for skinning over existing walls — not a substitute for new work. When in doubt, match what’s already in the house and confirm with local code.

Screws, tape, and mud

As a rule of thumb, plan roughly 30 screws per 4×8 sheet — screws every 12–16 inches on studs and joists, with the exact fastening schedule set by your local code. Tape covers every joint, and compound usage depends on how many joints and what finish level you’re chasing. Rather than estimating finishing materials separately, our drywall material calculator rolls screws, tape, and joint compound into the same estimate so you buy everything once.

Hanging orientation: horizontal vs. vertical

Pros hang 4×8 sheets horizontally on walls: two 4-ft courses cover an 8-ft wall, the long tapered factory edges land at 4 ft — a comfortable finishing height — and horizontal sheets bridge more studs, which makes a flatter wall. Vertical hanging has its place: 9-ft and taller walls (where horizontal leaves an awkward strip), and solo DIYers who find a vertical sheet easier to lift into place. Either way, keep factory edges meeting factory edges wherever possible — tapered edges make nearly invisible joints, while cut edges don’t. And stagger the butt joints between courses like brickwork, so no four sheet corners ever meet at a single point.

Cutting tips that protect your sheet count

Score the face paper with a sharp utility knife, snap the gypsum core, then slice the back paper — a dull blade tears the face and wastes the sheet. Cut outlet and switch boxes with a rotary spiral saw after the sheet is tacked up, not before; mismeasured pre-cuts are the top sheet-killer on DIY jobs. Hang the ceiling first, then the walls, so the wall sheets support the ceiling edges. And save your large offcuts: the strips above doors and below windows come from them, which is exactly what the waste allowance is for.

Insulate before you hang

Drywall goes up once — and once it’s up, the wall cavities are closed for years. If the room needs insulation, now is the moment: our insulation calculator estimates batts, rolls, or blown-in for the same walls and ceiling. And when the mud is sanded and the paint goes on, the paint calculator sizes the job in gallons.

How we calculate

Wall area = room perimeter × ceiling height; ceiling area = length × width. Sheet counts divide by 32 ft² per 4×8 sheet (48 ft² per 4×12), with walls and ceiling rounded up separately since wall offcuts rarely cover a ceiling efficiently. Openings under ~20 ft² are not deducted — cutting waste absorbs them. The 10% allowance covers cuts, damage, and unusable offcuts; it is a planning figure, not a bid quantity.

Reviewed September 2026 · TrueMeasure

Frequently asked questions

Is 17 sheets for walls only, or walls and ceiling?

Walls and ceiling: 12 sheets cover the walls and 5 cover the ceiling of a 12×12 room with 8-ft ceilings. Walls alone need 12 sheets before waste.

Should I buy 4×8 or 4×12 sheets?

4×12 sheets mean fewer joints and less taping — 11 sheets vs. 17 for a 12×12 room — but they’re harder to transport and maneuver. 4×8 sheets fit in most vehicles and through standard doorways.

Do I subtract doors and windows from drywall area?

Small openings: no — offcuts and the waste allowance absorb them. Large openings (sliding doors, big picture windows, open entries): yes, deduct the area but keep a waste allowance.

How thick should drywall be?

½-inch is standard for walls. Use ⅝-inch for ceilings on 24-inch framing and anywhere fire code requires it (garages, some multifamily work). Confirm with local code.

How many drywall screws do I need per sheet?

Roughly 30 per 4×8 sheet as a planning figure — a 12×12 room’s 17 sheets need about 500 screws. Buy by the box; running short mid-job is worse than leftovers.

You’ll also need

Drywall calculatorPaint calculatorInsulation calculator