Drywall Calculator
Work out how many sheets of drywall you need for a room from wall and ceiling area, openings and waste. Example: a 12 by 14 foot room with 8 foot walls and a ceiling needs 20 sheets of 4 by 8 foot drywall with 10% waste.
Show steps
How to use the Drywall Calculator
- Enter the room length, width and wall height.
- Choose whether to include the ceiling and enter the area of doors and windows.
- Pick the sheet size and waste allowance, then press Calculate.
Formula and method
Wall area = 2 x (length + width) x height. Ceiling area = length x width. Net area = walls + ceiling – openings. Sheets = net area x (1 + waste) / area of one sheet, rounded up.
Worked example: 14 x 12 ft room, 8 ft walls, ceiling
| Step | Result |
|---|---|
| Walls: 2 x (14 + 12) x 8 | 416 sq ft |
| Ceiling: 14 x 12 | 168 sq ft |
| Minus 40 sq ft of openings | 544 sq ft |
| With 10% waste | 598 sq ft |
| Sheets of 32 sq ft | 19 |
Sheets for walls only (8 ft walls, 10% waste)
| Room | Wall area | 4 x 8 sheets |
|---|---|---|
| 10 x 10 ft | 320 sq ft | 11 |
| 12 x 12 ft | 384 sq ft | 14 |
| 12 x 14 ft | 416 sq ft | 15 |
| 14 x 16 ft | 480 sq ft | 17 |
| 16 x 20 ft | 576 sq ft | 20 |
Tips
Hang ceiling sheets first. Use 1/2 inch board for walls and 5/8 inch for ceilings or fire-rated areas. Stagger seams, and order a little extra for mistakes.
Frequently asked questions
How many sheets of drywall do I need?
Divide the area to cover by 32 for 4 x 8 sheets, after adding waste.
How much waste should I allow?
About 10%.
How big is a sheet of drywall?
Commonly 4 x 8 feet, or 32 square feet.
Should I subtract windows and doors?
Yes for large openings, but many pros do not subtract small ones.
How thick is drywall?
1/2 inch for walls and 5/8 inch for ceilings or fire-rated walls are typical.
How much joint compound do I need?
Roughly one 4.5 gallon bucket per 400 to 500 sq ft of board.
Sources
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