How many sheets of drywall do I need for a 12×12 room?

A 12×12 room with 8-ft ceilings: four walls = 4 × (12 × 8) = 384 sq ft, minus one door (21 sq ft) = 363 sq ft + ceiling (144 sq ft) = 507 sq ft total. With 10% waste, divided by 32 sq ft per sheet: about 18 sheets of 4×8.

What size drywall sheets should I use?

4×8 sheets for most walls and low-ceiling rooms (8 ft). 4×12 or 4×10 for 9–10 ft ceilings — fewer seams means less taping. Ceilings: use 5/8-inch thick, 4×12 if possible. Horizontal installation on walls reduces butt joints and produces a better finish.

Should I subtract windows and doors from my drywall calculation?

For precise material ordering, yes — subtract openings. For a conservative estimate, many contractors don't subtract windows and doors, letting the extra material cover waste. In rooms with many large openings, always subtract to avoid over-ordering significantly.

What type of drywall do I need in a bathroom?

Moisture-resistant drywall (green board) for bathroom walls away from the shower/tub. Cement board (Durock or HardieBacker) for shower and tub surrounds — standard drywall including green board cannot withstand direct water contact. Regular drywall on dry bathroom walls is fine.

How much drywall joint compound do I need?

Approximately 3–4 gallons of pre-mixed all-purpose joint compound per 500 sq ft of drywall. A typical 5-gallon bucket covers about 500–700 sq ft. You'll apply 3 coats (tape coat, first fill coat, finish coat) — heavier application in corners and around fasteners.

Drywall Calculator: How Many Sheets Do You Need for Any Room?

Calculate drywall sheets needed for walls and ceilings. Covers standard sheet sizes, how to handle windows and doors, waste factors, and typical drywall types by location.

Related Calculators

Drywall Calculator
Estimate drywall sheets, joint compound and screws from room perimeter, wall height, ceiling area, openings and waste allowance.

Standard Drywall Sheet Sizes

Sheet Size	Area	Best Use
4×8 ft	32 sq ft	Most rooms, DIY-friendly
4×10 ft	40 sq ft	9-ft ceilings
4×12 ft	48 sq ft	10-ft ceilings, fewer seams
4×16 ft	64 sq ft	Commercial, low-seam jobs

The most common residential choice is 4×8 for walls and 4×12 for ceilings (fewer seams = less taping work).

How to Calculate Drywall Sheets

Step 1: Measure all wall and ceiling surfaces

For each wall: length × height = square footage For ceiling: room length × room width = square footage

Step 2: Subtract openings

Standard door (3×7 ft): 21 sq ft
Window (3×4 ft): 12 sq ft
Smaller windows: measure actual rough opening

Note: A common shortcut for beginners is to NOT subtract openings — the extra material accounts for waste and cuts around openings. This works for rooms with few openings.

Step 3: Divide by sheet area and add waste

For 4×8 sheets (32 sq ft each): Total sq ft ÷ 32 × 1.10 (10% waste)

For 4×12 sheets (48 sq ft each): Total sq ft ÷ 48 × 1.10

Always round up to the next whole sheet.

Worked Example: 12×14 ft Bedroom, 9-ft Ceilings

Surface	Dimensions	Sq Ft
Wall A (long)	14 × 9 ft	126
Wall B (long)	14 × 9 ft	126
Wall C (short)	12 × 9 ft	108
Wall D (short, door)	12 × 9 ft − (3×7)	87
Ceiling	12 × 14 ft	168
Total net area		615 sq ft

Sheets needed (4×8, 32 sq ft each): 615 ÷ 32 × 1.10 = 21.2 → 22 sheets Sheets needed (4×12, 48 sq ft each): 615 ÷ 48 × 1.10 = 14.1 → 15 sheets

Drywall Types by Location

Type	Code	Use
Standard whiteboard	—	Interior walls and ceilings
Moisture-resistant (green board)	MR	Bathrooms (not suitable for shower surrounds)
Cement board (Durock)	—	Shower surrounds, wet areas
Fire-rated (Type X)	Type X	Garages (NFPA requirement), attached garage walls
Soundproof drywall	—	Home theaters, bedrooms adjacent to noisy areas

Garage requirement: NFPA 13D and most local codes require 5/8-inch Type X drywall on the garage side of walls and ceilings that separate the garage from living space.

Thickness Selection

Thickness	Common Use
1/4 inch	Curved surfaces, second layer over existing
3/8 inch	Repairs, second layers
1/2 inch	Standard walls and ceilings (most common)
5/8 inch	Ceilings (sag-resistant), fire-rated assemblies

For ceilings, 5/8-inch drywall is preferred for spans over 16 inches on center to prevent sagging.

Additional Materials Needed

Per 500 sq ft of drywall: - Joint compound (all-purpose mud): 3–4 gallons - Joint tape: ~200 linear feet - Drywall screws (1-5/8 inch for walls): 1–2 lbs (approximately 6 screws per sheet) - Corner bead: measure all outside corners in linear feet

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Frequently Asked Questions

How many sheets of drywall do I need for a 12×12 room?: A 12×12 room with 8-ft ceilings: four walls = 4 × (12 × 8) = 384 sq ft, minus one door (21 sq ft) = 363 sq ft + ceiling (144 sq ft) = 507 sq ft total. With 10% waste, divided by 32 sq ft per sheet: about 18 sheets of 4×8.
What size drywall sheets should I use?: 4×8 sheets for most walls and low-ceiling rooms (8 ft). 4×12 or 4×10 for 9–10 ft ceilings — fewer seams means less taping. Ceilings: use 5/8-inch thick, 4×12 if possible. Horizontal installation on walls reduces butt joints and produces a better finish.
Should I subtract windows and doors from my drywall calculation?: For precise material ordering, yes — subtract openings. For a conservative estimate, many contractors don't subtract windows and doors, letting the extra material cover waste. In rooms with many large openings, always subtract to avoid over-ordering significantly.
What type of drywall do I need in a bathroom?: Moisture-resistant drywall (green board) for bathroom walls away from the shower/tub. Cement board (Durock or HardieBacker) for shower and tub surrounds — standard drywall including green board cannot withstand direct water contact. Regular drywall on dry bathroom walls is fine.
How much drywall joint compound do I need?: Approximately 3–4 gallons of pre-mixed all-purpose joint compound per 500 sq ft of drywall. A typical 5-gallon bucket covers about 500–700 sq ft. You'll apply 3 coats (tape coat, first fill coat, finish coat) — heavier application in corners and around fasteners.

Last updated 7/28/2026