Drywall Calculator — Sheets, Cost & Accessories
Estimate how many sheets of drywall (sheetrock/gypsum board) a room requires in imperial feet. Deducts standard door and window openings, adds a 10% waste margin, and optionally calculates material cost.
ft
ft
ft
Include ceiling
Sheet size
$
Includes 10% waste; doors and windows deducted
- 1
Wall perimeter
2 × (12 + 10) = 44 - 2
Wall area
44 × 8 = 352 - 3
Gross area (walls + ceiling)
352 + 120 = 472 - 4
Net area
472 − 44 = 428Standard doors (20 sq ft each) and windows (12 sq ft each) deducted. - 5
With 10% waste
428 × 1.10 = 470.8 - 6
Sheets needed
⌈470.8 ÷ 32⌉ = 15
How does this calculator work?
Total drywallable area = perimeter × height + ceiling (optional), minus door (20 sq ft each) and window (12 sq ft each) deductions. Add 10% for waste, divide by sheet area (32 sq ft for a 4 × 8 ft sheet) and round up. Budget roughly 32 screws per sheet plus tape and joint compound.
Formula
How this is calculated
The calculator computes the gross surface area to be drywalled: the room perimeter (2 × (length + width)) times the wall height, plus the ceiling area (length × width) if selected. From this gross area it subtracts estimated opening areas — a standard door is assumed to be 2.5 ft wide × 8 ft tall (20 sq ft) and a standard window 3 ft × 4 ft (12 sq ft). Adjust the number of doors and windows to suit your actual layout; for large or non-standard openings, measure and add a custom offset to the room dimensions.
The net area is increased by 10% for waste — cuts around outlets, corners, and inevitable mistakes — then divided by the area of one sheet (a 4 × 8 ft sheet covers 32 sq ft; 4 × 10 and 4 × 12 are also available) and rounded up to a whole number. Accessories are estimated from the sheet count: roughly 32 screws per sheet, 0.45 linear feet of joint tape per square foot of net area, and about 0.016 lb of joint compound per square foot for taping and first coat.
Labour cost is not included — drywall labour varies widely by region and finish level (smooth, Level 5, textured). Use the material cost field for a quick budget figure from your local sheet price.
Frequently asked questions
It subtracts standard-size estimates: 20 sq ft per door (2.5 ft × 8 ft) and 12 sq ft per window (3 ft × 4 ft). For non-standard sizes, measure the actual opening area and adjust the room length or width slightly to compensate. Many professionals skip the deduction anyway as the extra sheets cover cuts at corners and above doors.
Drywall is sold in whole sheets, and cuts at corners, outlets, windows, and the tops of walls leave off-cuts that cannot usually be used elsewhere. A 10% waste allowance is a standard industry rule of thumb; increase it to 15% for rooms with many angles, curves, or arched openings.
The 4 × 8 ft (32 sq ft) sheet is by far the most common and easiest to handle alone. 4 × 12 ft sheets mean fewer seams and less taping for rooms with 9–10 ft ceilings, but require two people and a taller lift. Match the sheet length to your wall height where possible to minimise horizontal seams.
Also known as
TG we-Calculate Editorial Team. (2026). Drywall Calculator — Sheets, Cost & Accessories [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/drywall-calculator
TG we-Calculate Editorial Team. "Drywall Calculator — Sheets, Cost & Accessories." TG we-Calculate. 2026. https://we-calculate.com/calculator/drywall-calculator.
TG we-Calculate Editorial Team, "Drywall Calculator — Sheets, Cost & Accessories," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/drywall-calculator
@misc{wecalculate_drywall_calculator, title = {Drywall Calculator — Sheets, Cost & Accessories}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/drywall-calculator}}, year = {2026}, note = {TG we-Calculate} }
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