Interior & Finishes

Drywall Calculator

This drywall calculator counts the sheets a room needs for walls and ceiling; see our drywall installation guide for finish levels and costs. Estimate drywall (gypsum board, Sheetrock®) for a rectangular room. Enter the room size and whether to include the ceiling; the calculator subtracts openings, adds waste and divides by the sheet size you plan to hang. Longer sheets mean fewer butt joints but are heavier and harder to carry up stairs.

Results from this drywall calculator are planning estimates; confirm quantities and prices with your supplier or contractor before you order.

Your results will appear here

Enter your measurements and press Calculate. Defaults show a typical example.

How to use the drywall calculator

Enter room length, width and wall height.
Tick "Include the ceiling" if you are hanging it too.
Count doors and windows.
Choose your sheet size and a waste allowance.

Formula

Area = 2 × (L + W) × H − openings (+ L × W for the ceiling). Sheets = area × (1 + waste) ÷ sheet area, rounded up.

Worked example

A 12 × 12 ft room with 8 ft walls, ceiling, one door and one window: 349 + 144 = 493 sq ft. With 10% waste, 542 ÷ 32 = 17 sheets of 4×8.

Tips for using the drywall calculator

Longer sheets mean fewer butt joints, which are the hardest seams to finish well.
Use moisture-resistant board in bathrooms and fire-rated board where code requires it.
Order screws, tape and joint compound with the sheets so work does not stall.
Plan sheet direction before ordering: hanging sheets horizontally on walls usually means fewer seams at eye level, while ceilings go up first so wall sheets support their edges. Stack sheets flat to keep them from bowing.