Drywall Calculator
Estimate drywall sheets using room dimensions or a known total area, including ceilings, openings, waste, and sheet size.
Drywall calculator
Measurement system
Rooms
Project settings
Results
Drywall sheets needed
—
Wall area (calculated)—
Ceiling area (calculated)—
Openings deducted (calculated)—
Calculated area from rooms—
Manually entered area—
Net drywall area—
Waste allowance—
Total drywall area including waste—
Selected sheet size—
Area per sheet—
Estimated sheet cost—
Worked example
For a 12 × 12 ft room with an 8 ft ceiling and one 3 × 6 ft door:
Wall area = 2 × (12 + 12) × 8 = 384 ft²
Ceiling area = 12 × 12 = 144 ft²
Gross area = 384 + 144 = 528 ft²
Door area = 3 × 6 = 18 ft²
Net area = 528 − 18 = 510 ft²
With 10% waste = 510 × 1.10 = 561 ft²
If the selected sheet is 4 × 8 ft = 32 ft² each, 561 ÷ 32 = 17.53
Round up to 18 sheets.
Frequently asked questions
Measure the room area to be covered, subtract any openings you are not covering, and then add waste. The calculator then divides the final total area by the selected drywall sheet size and rounds up to the next whole sheet.
The answer depends on wall height, whether the ceiling is included, openings such as doors and windows, the sheet size, and your waste allowance. A 12 × 12 room with an 8 ft ceiling and a 4 × 8 ft sheet size will often be close to 18 sheets with typical waste, but the exact count varies.
A default allowance of 10% is included and is editable. That is a reasonable starting point for straightforward rooms, but more complex layouts, angled walls, or a lot of cuts may justify a different waste percentage.
Yes, if those openings will not receive drywall. This calculator supports either measured individual door and window openings or a manually entered total opening area, so you can deduct the actual area you are not covering without double-counting.
If the room has angled, irregular, or complex walls, measure the actual drywall area directly. For that room, select Enter area. Enter the area requiring drywall coverage before waste. The calculator applies the selected waste percentage afterward.
Sheet availability and the best size for the job depend on the project and local market. The calculator includes common presets plus a Custom option so you can match the sheet size you are buying or planning to use.