Drywall Calculator (Sheets)

Enter the room size, whether to include the ceiling, the area of large openings and the panel size.

How it works

Wall area = 2 × (length + width) × height. Area to cover = walls + ceiling (length × width, if included) + extra − large openings. Sheets = area × (1 + allowance) ÷ sheet area, rounded up. USG lists 4 × 8 = 32, 4 × 10 = 40 and 4 × 12 = 48 sq ft per panel.

Worked example: 12 × 12 ft room, 8 ft walls, with ceiling: 2 × 24 × 8 = 384 + 144 = 528 sq ft. 528 ÷ 32 = 16.5, so 17 sheets of 4 × 8 (USG's coverage table: 17 panels = 544 sq ft), or 528 ÷ 48 = 11 sheets of 4 × 12.

Assumptions

USG says to subtract large openings such as doorways and picture windows, but not small ones such as electrical boxes and pipe fittings. Measure your own openings; no standard door size is assumed.
Waste default 10%, as Lowe's drywall buying guide suggests. Layout, ceiling height and how well offcuts can be reused change the real waste.
Rectangular room with walls of equal height. Joint compound, tape, screws and corner bead are not included.
Panel type and thickness (for example moisture-resistant or fire-rated) can be set by local codes; check local codes.
This is a quantity estimate only. Follow the product's installation instructions and check local codes.

Frequently asked questions

How many sheets of drywall for a 12 × 12 room?

With 8 ft walls and the ceiling: 384 + 144 = 528 sq ft. That is 16.5, so 17 sheets of 4 × 8 before any allowance, or 11 sheets of 4 × 12. With 51 sq ft of openings and 10% extra: 524.7 sq ft, 17 sheets of 4 × 8.

How many square feet is a sheet of drywall?

USG lists 32 sq ft for 4 × 8, 40 for 4 × 10 and 48 for 4 × 12 panels.

How much extra drywall should I buy?

Lowe's suggests adding about 10% for cuts and waste.

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Sources

Formulas and reference values are from these sources. Page content last updated 2026-10-19.