How to use this calculator
- Enter or choose units.
- Enter or choose room length.
- Enter or choose room width.
- Enter or choose wall height.
- Enter or choose doors and windows (total area).
- The sheets to buy updates as you type. Use Copy result or Share to keep it.
Method
Area = 2(L + W) × H − Openings (+ L × W); Sheets = ⌈Area × (1 + Waste) ÷ Sheet area⌉
- L, W, H
- room length, width and wall height
- Sheet area
- e.g. 4 × 8 ft = 32 ft², 1.2 × 2.4 m = 2.88 m²
Worked example
- Walls = 2 × (12 + 10) × 8 = 352 ft² − 40 ft² openings = 312 ft².
- Plus ceiling 12 × 10 = 120 ft² → 432 ft².
- 432 × 1.10 ÷ 32 ft² = 14.85 → 15 sheets.
A 12 × 10 ft room with 8 ft walls and its ceiling needs 15 sheets of 4 × 8 drywall with 10% waste.
What the result means
Longer sheets mean fewer joints to tape; boards for ceilings and wet areas may be a different type. Buy screws, tape and compound by area too.
Assumptions and limits
- One layer of board on each surface.
- Sloped ceilings, soffits and bulkheads need to be added separately.
Questions
Should I subtract doors and windows?
Subtract large openings, but many installers leave small windows in because the cut-outs are mostly waste anyway.
Please note: Quantities are estimates. Confirm requirements with your engineer or supplier before ordering materials.