🧱 Drywall Sheet Calculator

Estimate how many drywall (sheetrock) panels you need for a simple rectangular room. Enter room length, width, wall height, openings, sheet size, and waste factor to get a clear drywall sheet count and surface area breakdown for walls and ceilings.

Drywall sheet calculator results

Enter your room size, openings, and drywall sheet dimensions, then choose Calculate Drywall Sheet Count to see how many panels you'll need for the project.

Drywall area and sheet breakdown

After you run a calculation, this section shows the wall area, ceiling area, openings, waste-adjusted area, and sheet count in one place for quick reference.

Drywall calculator inputs and key terms

This calculator focuses on a simple rectangular room, which covers many bedrooms, offices, and small remodels. Here's what each input means.

• Room length and width (feet): The interior floor dimensions of the room measured wall-to-wall. These control the size of the perimeter and the ceiling.
• Wall height (feet): The distance from finished floor to finished ceiling. Typical heights are 8′, 9′, or 10′.
• Include ceiling: Choose whether to include the ceiling in the drywall calculation. Many projects require both walls and ceiling to be covered; some use alternative ceiling finishes.
• Area of openings (ft²): The combined surface area of doors, windows, large openings, and other features that will not be covered with drywall. Subtracting openings gives a more precise sheet count.
• Waste factor (%): A percentage added to account for offcuts, mistakes, and layout constraints. Straightforward rooms often use 10–15% waste; complicated layouts may use more.
• Drywall sheet length and width: The size of the drywall panels you plan to install. Standard panels are 4′ wide and 8′ long (32 ft²), but 10′ and 12′ lengths are common in taller rooms to reduce seams.
• Square foot (ft²): A unit of area equal to a square 1 foot by 1 foot. Drywall coverage is typically estimated in square feet.
• Sheet count: The total number of drywall panels the calculator estimates you'll need, rounded up to a whole sheet.

Formulas used in the Drywall Sheet Calculator

These formulas are standard for quick drywall takeoffs in residential and light commercial work. All dimensions are kept in feet and square feet for consistency.

1. Wall area

Let:
L = room length (ft)
W = room width (ft)
H = wall height (ft)
There are four walls in a rectangular room. Two are L × H and two are W × H:
Wall area (ft²) = 2 × H × (L + W)

2. Ceiling area

If you choose to include the ceiling:
Ceiling area (ft²) = L × W

3. Net area and waste factor

Let:
Aopen = total area of openings (ft²)
p = waste factor (%) as a whole number (for example, 10 for 10%)
Gross area = Wall area + Ceiling area
Net area (ft²) = Gross area − Aopen
Waste multiplier:
k = 1 + (p ÷ 100)
Area with waste (ft²) = Net area × k

4. Sheet area and sheet count

Let:
Ls = sheet length (ft)
Ws = sheet width (ft)
Sheet area (ft²) = Ls × Ws
Required sheets = Area with waste ÷ Sheet area
The calculator rounds the required sheets up to the next whole number:
Sheet count = ceil(Required sheets)

In practice, installers also consider seam layout, stud spacing, and board orientation (horizontal vs. vertical), but these geometric formulas provide a reliable starting point for sheet quantity.

Drywall Sheet Calculator FAQs

• How accurate is this drywall sheet calculator?
  The calculator gives a solid estimate for simple rectangular rooms. It accounts for wall and ceiling area, subtracts openings, and adds a waste factor. Real projects may need extra sheets for complicated layouts, soffits, bulkheads, or future repairs, so many installers round up a bit beyond the calculated result.
• What waste percentage should I use for drywall?
  For straightforward rooms with an experienced installer, a waste factor of 10–15% is common. Complex layouts with many corners, angles, or cutouts might justify 15–20%. If you're unsure, it's usually safer to err slightly on the high side than run short in the middle of a job.
• Should I use 8′, 10′, or 12′ drywall sheets?
  Many 8′-tall rooms use 8′ sheets installed horizontally to reduce seams. Taller rooms may benefit from 10′ or 12′ sheets to minimize horizontal joints. The best choice depends on wall height, stud layout, and how comfortable you are handling longer, heavier panels.
• Does this calculator handle multiple rooms or odd shapes?
  This version focuses on a single rectangular room. For multi-room projects or irregular spaces, you can run separate calculations for each room or section and add the sheet counts together. For large or complex jobs, a detailed takeoff from plans is still recommended.
• Does the sheet count include ceilings by default?
  You can choose whether to include the ceiling in the calculation. When you select “Yes,” the calculator adds L × W to the wall area. When you select “No,” only the walls are included. This is helpful if the ceiling uses a different finish like wood planks or acoustic tiles.
• Do I need to subtract every small opening for an accurate result?
  Subtracting the total area of doors and larger windows improves accuracy, especially in rooms with many openings. Small outlets, vents, and fixtures typically do not need to be subtracted; the waste factor usually covers those minor cutouts.