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- A 14 × 12 ft room with 8 ft ceilings, one door and two windows needs 19 sheets of 4 × 8 drywall, walls and ceiling.
- The surface to cover is 533 sq ft, or 586.3 sq ft with 10% waste.
- Plan on about 608 screws, 198 ft of joint tape and 5.3 gallons of joint compound.
- At $15 a sheet the drywall costs about $285.
How to use the drywall calculator
Enter the room size
Type the length, width and ceiling height in feet.
Choose what you are covering
Pick walls only, ceiling only, or both.
Add doors and windows
Each door removes about 21 sq ft and each window about 15 sq ft from the wall area.
Pick the sheet size and waste
Choose 4 × 8, 4 × 10 or 4 × 12 sheets. Keep 10% waste, or raise it to 15% for rooms with many corners.
How the drywall count is calculated
Drywall formula
Wall area = 2 × (length + width) × height
Net area = wall area − openings + ceiling area (length × width)
Sheets = net area × (1 + waste %) ÷ sheet area, rounded up
Screws use about 32 per sheet, tape about 0.37 ft per sq ft and joint compound about 1 gallon per 100 sq ft. These are rules of thumb.
Worked example: a 14 × 12 ft room
The ceiling is 8 ft high. The room has one door and two windows, and you cover the walls and ceiling with 4 × 8 sheets and 10% waste.
- Wall area (2 × 26 × 8) 416 sq ft
- Openings (21 + 2 × 15) −51 sq ft
- Ceiling (14 × 12) 168 sq ft
- Total to cover 533 sq ft
- With 10% waste 586.3 sq ft
- Sheets (586.3 ÷ 32 = 18.3) 19
- Screws (19 × 32) 608
- Joint tape 198 ft
- Joint compound 5.33 gallons
At $15 per sheet, the sheets cost $285.
Drywall calculator FAQ
How many sheets of drywall do I need?
Divide the total area by the area of one sheet and round up after adding waste. A 4 × 8 sheet covers 32 sq ft.
How much waste should I add?
About 10% for a simple room. Use 15% for rooms with many corners, angles or openings.
Do I subtract doors and windows?
Yes. The calculator removes about 21 sq ft per door and 15 sq ft per window. Small windows can be left in if you want extra material.
How many screws per sheet?
A common rule is about 32 screws for a 4 × 8 sheet. Local code or the manufacturer may call for different spacing.
How much joint compound do I need?
A rough guide is one gallon per 100 sq ft of drywall. Your finish level and experience change the amount.
Should I use 4 × 8 or 4 × 12 sheets?
Larger sheets have fewer seams but are harder to carry and hang. For ceilings and small rooms, 4 × 8 or 4 × 10 is usually easier.