Construction desk
Drywall Calculator
Estimate drywall sheets for a wall after deducting openings.
Drywall Calculator: Estimate the number of drywall sheets needed to cover a wall run after subtracting door and window openings. Enter the dimensions of the sheet you intend to buy and a cutting allowance. The result rounds the net surface requirement to whole sheets, giving an area-based starting point for a panel layout. Runs 100% locally in your browser with zero server file uploads.
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Sheets to buy (estimate)
9 sheets
- Net wall area (estimate)
- 240 sq ft
Sheets = ceiling((wall area − openings) × (1 + waste) ÷ sheet area)- Every result is an estimate; verify surface preparation, measurements, and local practices before ordering.
- Allow for the stated waste and product-coverage assumptions; openings are deducted only where requested.
- Compaction, settling, substrate condition, cuts, and installation method can change actual quantities.
Formula and worked example
Sheets = ceiling((wall area − openings) × (1 + waste) ÷ sheet area)
A worked example with sample values:
| Inputs | |
|---|---|
| Wall length | 40 ft |
| Wall height | 8 ft |
| Openings | 80 sq ft |
| Sheet length | 8 ft |
| Sheet width | 4 ft |
| Waste allowance | 10% |
| Results | |
|---|---|
| Net wall area | 240 sq ft |
| Sheets to buy (estimate) | 9 sheets |
Net wall area and sheet rounding
Let L be wall run in feet, H wall height, O uncovered openings in ft², S sheet length, B sheet width and w cutting waste as a percentage. Net area = L × H − O. Sheets = ceiling(net area × (1 + w ÷ 100) ÷ (S × B)). Ceiling means rounding upwards to the next whole sheet.
A 40 ft run at 8 ft high has 320 ft² gross area. Subtract 80 ft² of openings to leave 240 ft². With illustrative 10% waste, allow 264 ft². An 8 ft × 4 ft sheet covers 32 ft²; 264 ÷ 32 = 8.25, so the calculator returns 9 sheets. Those sheet dimensions are example inputs, not a prescribed board size.
Panel layout and measurement
USG's installation guide (https://www.usg.com/content/dam/USG/pdpmovedocuments/sheetrock-gypsum-panels-installation-guide-en-can.pdf) illustrates panel orientation, cutting and cutouts. Use the selected board's installation instructions to plan supported edges; this sheet count does not determine fastener spacing or a fire-rated assembly.
To compare a metric take-off, multiply ft² by 0.09290304 to obtain m² using NIST's area factor (https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8). Convert both sheet and wall dimensions consistently. Tape, compound, corner bead and screws need separate quantities rather than another percentage of sheet area.
How to use it
- Enter measurements using the units shown beside each field.
- Choose the product coverage and allowances for your measured job.
- Calculate, then compare the rounded quantity with your layout and product label.
Privacy & limitations
Inputs and calculations stay in your browser. No values are uploaded.
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Frequently asked questions
Should every door and window be deducted from drywall area?
Only deduct measured openings that will not receive board. A cutout may still consume most of a sheet, so subtracting its area can understate the purchase quantity. Openings must remain smaller than the gross wall area; use a layout drawing to check reusable offcuts.
How do I count ceilings or a second layer of board?
Calculate the ceiling as a separate surface using its own dimensions. Repeat the calculation for each required layer or face of a partition. This page counts one layer on one entered surface and does not automatically double the result.
Does nine sheets mean nine sheets will fit my wall?
No. Area division does not place seams, avoid joints near openings or ensure that edges land on suitable framing. A narrow remaining strip may require another full panel. Select an allowance from your cutting plan and check the product label for panel suitability.
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