Drywall Calculator
Sheets of drywall needed for walls and ceiling, after door/window deductions.
🔒 Runs entirely in your browser — nothing here is ever uploaded
About the Drywall Calculator
Calculates how many drywall sheets to buy for a room's walls (and optionally ceiling), from room dimensions, door/window openings, sheet size, and a waste buffer — rounding up to whole sheets since drywall is sold by the panel.
- Enter the room's length, width, and wall height.
- Choose whether to include the ceiling.
- Enter the number of doors and windows.
- Choose your sheet size and a waste buffer.
- Read the number of sheets to buy.
A 12ft × 10ft room with 8ft walls, no ceiling, 1 door, 2 windows, using 4×8 sheets and a 10% waste buffer: net area of 301 sq ft, 331 sq ft with waste, requiring 11 sheets.
| Sheet size | Coverage |
|---|---|
| 4 × 8 ft | 32 sq ft |
| 4 × 10 ft | 40 sq ft |
| 4 × 12 ft | 48 sq ft |
Door and window deductions use standard-size assumptions (~21 sq ft per door, ~15 sq ft per window) — a rule of thumb, not your exact openings. A 10% waste buffer is typical for a simple rectangular room; use 15% for rooms with more corners, angles, or cuts. This calculator only computes sheet count — it doesn't size joint compound, tape, screws, or corner bead.
- • Larger sheets (4×12) mean fewer seams to tape and mud, but are heavier and harder to maneuver alone.
- • A 10% waste buffer covers typical cutting waste for a simple room; bump it to 15%+ for rooms with lots of corners or angled walls.
- • This tool doesn't size fasteners, tape, or joint compound — budget roughly 1 gallon of joint compound and 370 ft of tape per 500 sq ft as a separate rule of thumb.
- SpecCalc — Drywall Sheet Calculator — accessed 2026-08-30