Drywall Calculator
Enter total wall length and height, subtract any large openings, and pick a sheet size to get a waste-adjusted sheet count.
How it works
Gross wall area is total wall length times height. Subtracting door and window openings gives net area. Dividing by the chosen sheet's coverage gives the raw sheet count, and multiplying by (1 + waste % ÷ 100) then rounding up gives the sheets to buy.
Worked example
40 ft of wall at 8 ft high is 320 sq ft gross. Subtracting 40 sq ft of doors and windows leaves 280 sq ft. At 32 sq ft per 4×8 sheet with 10% waste: 280 ÷ 32 = 8.75 sheets, × 1.10 ≈ 9.6, rounded up to 10 sheets.
Assumptions
- Walls are treated as a single total length and height; add multiple rooms' areas together before entering them here.
- Subtracting openings is optional — many estimators skip it to build in extra waste allowance for cuts.
- This does not account for ceiling drywall, corner bead, tape, or mud — estimate those separately.
Reference
General construction measurement practices: International Code Council (ICC).
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Frequently asked questions
How many sheets of drywall do I need?
Subtract large openings from total wall area, divide by sheet coverage, add waste percentage, and round up to a whole sheet.
Should I subtract every door and window opening?
Small openings are often ignored since a sheet still needs cutting around them; larger openings are commonly subtracted. Many estimators skip it entirely for extra waste margin.
Which drywall sheet size should I choose?
4x8 ft sheets are most common and easiest to handle; 4x10 or 4x12 reduce seams on tall or long walls but are heavier.