Drywall Calculator
Estimate how much drywall you need by area and depth — plus bags and total cost. Switch between imperial and metric units.
Drywall Calculator
Estimate how much you need — and the cost.
- sq meters 10.22
Quick coverage reference
A standard 4×8 ft sheet covers 32 sq ft; a 4×12 ft sheet covers 48 sq ft. Sheets = round up (wall + ceiling area × (1 + waste) ÷ sq ft per sheet).
How it's calculated
- Add about 10% for cuts around windows, doors, and outlets; more for rooms with many openings or angled ceilings.
Source: inchcalculator.com/drywall-calculator/ (4×8 = 32 sq ft, 10% waste cross-checked)
Common drywall uses
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</script>How much drywall do I need?
Drywall is sold by the sheet, and the standard sheet is 4 × 8 ft, covering 32 sq ft. To estimate, add up all the wall and ceiling area you're covering, add a waste allowance for cuts, then divide by the coverage per sheet.
The formula is sheets = total area (sq ft) × (1 + waste%) ÷ 32, rounded up. For walls, area is the room perimeter × ceiling height; add the ceiling itself if you're boarding it. A 12 × 12 ft room with 8 ft walls plus its ceiling works out to roughly 18–19 sheets at 10% waste. Switch to 4 × 12 ft sheets (48 sq ft) and you'll need fewer sheets with fewer butt seams to tape.
How to measure for drywall
Measure the walls
Add up each wall (length × height). A quick way for a room is perimeter × ceiling height.
Add the ceiling
If you're boarding the ceiling too, add its length × width to the wall total.
Add a waste factor
Keep 10% for cuts around doors, windows, and outlets. Most pros do not subtract small openings — the offcuts rarely reuse.
Read sheets needed
The calculator divides by 32 sq ft per sheet and rounds up. Enter 48 instead for 4 × 12 ft sheets.
Drywall sizing & buying tips
Longer 4 × 12 ft sheets cover more per piece and leave fewer butt joints to tape and finish — but they are heavier and harder to handle solo.
1/2 in is standard for walls; 5/8 in (often fire-rated) is used on ceilings and garages to resist sag and meet code.
Sheet count is only part of the job — joint compound, tape, and screws are separate. Plan roughly one box of screws per dozen sheets.
Drywall calculator FAQ
How many sheets of drywall do I need for a 12x12 room?
For 8 ft walls plus the ceiling, about 18–19 standard 4 × 8 ft sheets at 10% waste. Walls alone are roughly 14 sheets.
How do I calculate drywall sheets?
Add wall and ceiling area in square feet, multiply by 1 + your waste percentage, then divide by 32 (a 4 × 8 sheet) and round up.
How many square feet is a sheet of drywall?
A standard 4 × 8 ft sheet covers 32 sq ft. A 4 × 12 ft sheet covers 48 sq ft.
Should I subtract windows and doors?
For small openings, most installers do not — the leftover scrap covers the waste. Subtract only large openings like garage doors or wide archways.
How much extra drywall should I buy?
Add about 10% for cuts and breakage. Rooms with lots of corners, soffits, or angled ceilings can need 15%.