By Zencalcy Editorial TeamLast reviewed About us
Drywall is ordered in 4 × 8 sheets, plus joint compound, tape and screws. Measure the walls and ceiling, deduct large openings, and add 10% for cuts — a room with several windows and a door can lose 15% of the gross area.
Drywall sheets, screws, mud and tape for a room.
Area = L × W Units = ⌈Area × (1 + waste) ÷ coverage⌉ Cost = Units × price
One sheet covers 32 sq ft per 4 × 8 sheet. Units are rounded up because suppliers sell whole sheets, and the waste allowance covers cuts, mistakes and future repairs.
| Symbol | Meaning |
|---|---|
| L, W | Room length and width (or wall length and height). |
| A | Area to cover, in square feet. |
| w | Waste allowance as a percentage. |
| N | Number of sheets to buy, rounded up. |
A 12 × 8 ft wall is 96 sq ft; with 10% waste that is 3.3 sheets, so four. Add the ceiling at 120 sq ft and the same room needs eight.
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About 32 screws per 4 × 8 sheet on walls and 36 on ceilings, at 12 inches on centre in the field.
Results use standard construction estimating arithmetic: volumes from measured area and depth, unit weights from published material densities, and code-referenced spans or clearances where the page names a code. Quantities are rounded up to whole saleable units and include the stated waste allowance. These tools are planning aids, not structural design, and do not replace a licensed engineer, a local code check, or a contractor's site measurement.
Reference material used to build and check this calculator:
Last reviewed: September 2026. See how we build and check every tool on the about page.
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Content updated: September 2026