Drywall Calculator
A standard 4x8 sheet covers 32 square feet. A 12 by 12 ft room with 8-foot ceilings has 384 sq ft of wall area. With two standard 20 sq ft door openings, you have 344 sq ft of net wall area — 10.75 sheets before waste. Add 10% waste and round up to 12 sheets for walls, or 16 sheets if you include the ceiling.
Worked example: A master bedroom 14 by 16 ft with 9-foot ceilings. Walls: 2(14+16) x 9 = 540 sq ft minus 2 doors (40 sq ft) = 500 net sq ft. Ceiling: 14 x 16 = 224 sq ft. Total: 724 sq ft divided by 32 = 22.6 — round up to 25 sheets with 10% waste. Screws: 25 x 32 = 800 screws. Joint compound: 25 x 0.1 gal = 2.5 gallons.
Thickness guide: use 1/2-inch for standard interior walls. Use 5/8-inch Type X for garage-to-living-space fire walls and ceilings with 24-inch joist spacing.
Aliases: sheetrock is a brand name by USG Corporation. Wallboard and gypsum board mean the same product.
Fastener spacing: 8 inches in the field, 6 inches at edges. Use 1-1/4 inch drywall screws for 1/2-inch board on wood studs. Overdriving screws past the paper face reduces holding strength.
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Frequently Asked Questions
Is sheetrock the same as drywall?
Yes. Sheetrock is a brand name by USG Corporation that became a generic term. Wallboard, gypsum board, and drywall all refer to the same product — gypsum plaster sandwiched between two layers of paper.
When should I use 1/2-inch vs 5/8-inch drywall?
Use 1/2-inch for standard interior walls and most ceilings. Use 5/8-inch Type X for the garage side of walls shared with living space (required by most codes), for any ceiling with 24-inch joist spacing to prevent sag, and for fire-rated assemblies.
How many screws per 4x8 sheet of drywall?
Use approximately 32 screws per 4x8 sheet. Space screws every 8 inches along intermediate studs and every 6 inches at edges and ends. Use 1-1/4 inch drywall screws for 1/2-inch board on wood studs.
How many drywall sheets for a 12x12 room with 8-foot ceilings?
You need approximately 12 sheets for the walls (384 sq ft minus two door openings = 344 net sq ft, plus 10% waste). Add 5 more sheets for the ceiling (144 sq ft divided by 32 = 4.5, round up to 5). Total: 17 sheets.
How much joint compound do I need per sheet?
Budget 0.1 gallon per sheet for first-time installations — a 12-sheet job uses roughly 1.5 gallons. Buy premixed compound in 1-gallon buckets for small jobs; 5-gallon buckets for full-room projects.