Drywall calculator
Hanging drywall in a room, garage, or basement? Enter the wall dimensions and optional ceiling area, pick your sheet size, and this drywall calculator tells you how many sheets to buy — with waste for cuts and mistakes.
How the drywall calculation works
Drywall coverage is simple area math: wall area (length × height) plus any ceiling area, divided by one sheet’s coverage. A 4×8 ft sheet covers 32 square feet; 4×10 covers 40; 4×12 covers 48. The result always rounds up — you can’t hang half a sheet.
Don’t subtract small openings like doors and windows; the offcuts rarely fit elsewhere, so the waste allowance absorbs them. Only subtract very large openings such as garage doors.
sheets = ⌈(wall_area + ceiling_area) ÷ sheet_area × (1 + waste%)⌉
Drywall calculator FAQ
How many drywall sheets do I need for a 12×8 ft wall?
96 sq ft ÷ 32 sq ft per 4×8 sheet = 3 sheets, plus 10% waste = 3.3, rounded up to 4 sheets.
What size drywall sheet should I use?
4×8 ft is standard and easiest to handle. 4×12 ft sheets mean fewer seams on long walls and ceilings but need two people. Use ⅝-inch thick sheets for ceilings and fire-rated walls.
Should I subtract doors and windows?
No — offcuts from openings are mostly unusable, so keep the full area and let the 10% waste cover it. Subtract only very large openings.
How much waste should I add?
10% for simple rectangular rooms; 15% for rooms with angles, soffits, or many openings.
How many screws do I need per sheet?
Roughly 30–36 screws per 4×8 sheet when studs are 16 inches on center.
4×8 vs 4×12 sheets — which is better?
Longer sheets give fewer seams to tape, but they’re heavy and awkward. For DIY work, 4×8 is usually the practical choice.