Drywall Calculator
Calculate how many sheets of drywall a room needs, plus joint compound, tape and screws.
Last updated · View algorithm, constants and default inputs (JSON)
About this calculator
Estimate wall and optional ceiling board area, then add a 10% sheet allowance. Compound, tape and screw quantities use simple planning ratios and vary with layout and finishing method; use product guidance for a purchase list.
Worked example
calculated with the default values below
Room length 14 ft · Room width 12 ft · Wall height 8 ft · Include the ceiling Walls only · Subtract for doors and windows 40 sq ft · Sheet size 4 × 8 ft (32 sq ft) Wall area 416.0 sq ft · Total area to cover 376.0 sq ft · Sheets needed 13 · Joint compound 7.0 gal · Joint tape 150 ft · Screws needed 414
General background references
Disclaimer
These calculators provide planning estimates only. Building codes, wiring regulations and safety requirements differ by country and change over time, and nothing here replaces a licensed professional or a permit. For structural, electrical or gas work, follow local code and have the installation inspected.
Implementation source
This record describes the implementation used by this page. It is not independent validation. External references, when available, support only the stated formula or definition; estimates and custom rules retain their own assumptions.
Formula and variables
N = ⌈1.1 × A ÷ a_s⌉, A = 2(L + W)H + cLW − O
- L
- Room length (ft)
- W
- Room width (ft)
- H
- Wall height (ft)
- O
- Openings area (ft²)
- c
- Ceiling flag: 0 no, 1 yes
- a_s
- Sheet area (32, 40 or 48 ft²)
N rounded up after 10% waste; compound 0.5 gal/sheet, tape 0.4 ft/ft², screws 1.1/ft². A clamped at 0.
Frequently asked questions
How does it count sheets and compound?
For a 14 × 12 ft room with 8 ft walls, wall area is 416 sq ft. Subtracting 40 sq ft of openings leaves 376 sq ft. The default 4 × 8 sheet covers 32 sq ft, so with a 10% allowance the tool rounds up 376 ÷ 32 × 1.1 to 13 sheets. It then rounds 0.5 gallon per sheet up to 7 gallons of compound. Choosing a 4 × 10 sheet changes the sheet area to 40 sq ft.