Drywall Calculator: Sheets Needed and Cost

Use our simple drywall calculator to determine how many sheets you need for your project and the cost.

How to use this drywall calculator

Our drywall calculator helps you estimate the number of sheets of drywall you’ll need to cover a wall based on the size of the surface area and the size of each sheet of drywall. To make your calculator, enter the length and width of the wall you plan to cover with drywall. You’ll also enter a percentage for waste.

After entering those values, enter the sheetrock size, typically 4 ft. wide by 8 ft. long, along with the cost for each sheet. Once you plug in that data, the calculator will determine how many drywall sheets you need and the estimated total drywall cost.

Calculating how much drywall you need

Figuring out how many panels of sheetrock you need to purchase isn’t a complicated process.

Begin by calculating the total surface area of the walls and/or ceiling you’ll cover with drywall. Determine the area of the surface you’re covering by measuring its length and width and multiplying the two measurements. You’ll then need to account for waste from off-cuts by multiplying the surface area by the percentage of waste.

(Surface Length x Surface Width) x (1 + % Waste) = Total Square Footage Covered

After you’ve determined the area of the surface you’re covering, calculate the surface area of the sheets of drywall you’re using by multiplying the length of each sheet by its width.

Drywall Width x Drywall Length = Square Feet Per Drywall Sheet

Once you have the area of the surface you’re covering and the drywall sheets, you can determine how many drywall sheets you’ll need to complete the job.

Total Square Footage Covered ÷ Square Feet Per Drywall Sheet = Drywall Sheets Needed

Repeat these calculations for each surface you need to cover with drywall, then add the number for each surface to come up with the total number of drywall sheets you need for your entire drywall hanging project.

Example drywall calculation

Here’s an example to illustrate how you would calculate the number of drywall panels you need for a particular project. Let’s say you need to cover a 20 ft. by 9 ft. wall with 4×8 panels of sheetrock with 10% of the material being waste.

The total square footage is calculated as (20 x 9) x (1.10) = 198

Each sheet of 4×8 drywall covers 32 square feet, which is calculated as 4 x 8.

By dividing 198 by 32, we determine you’ll need 6.2 drywall sheets to cover the wall. Round that number up to the next whole number, which is 7, to get how many sheets you’ll need to purchase.

By entering the cost of each drywall sheet into the calculator, you can also estimate how much the drywall will cost. For example, if each sheet costs $15, you’ll pay about $105 (15 x 7) to cover the wall.

Drywall types and sizes explained

Drywall comes in various types, thicknesses, and sizes to suit different needs.


The most common type of drywall is white board, used for bedrooms, hallways, living rooms, and other places where moisture isn’t an issue.

Greenboard drywall, which has a wax green covering that resists moisture and mildew, is used for walls in bathrooms and kitchens and sometimes as a backer board for tile. Purple drywall, which has even better water resistance, is a good choice in areas where the walls will likely come into contact with water.

There are also less commonly used types of drywall. Blue board, or plaster board, is used as a backer board for veneer plastering. Type X drywall is a type of drywall made with fire retardant fiberglass that’s used in spaces that must meet stringent fire code requirements. There’s also laminated drywall that’s designed for soundproofing rooms.


The standard size for drywall is 4 feet wide by 8 feet high, though it is possible to find larger panels that are 4 feet by 12 feet for rooms with high ceilings and smaller pieces that are 2 feet by 2 feet for patching and repairing.


Drywall is available in 1/4-inch, 1/2-inch, and 5/8-inch thicknesses. 1/2-inch drywall is the most common for most interior walls and ceilings. Thicker 5/8-inch drywall is used for walls and ceilings that must adhere to certain fire prevention ratings. Thinner 1/4-inch drywall is typically used over existing drywall to hide imperfections.


  • What screws are best for drywall?

    The type of drywall screw you should use depends on the material of the studs that will be holding up the drywall. If you’re hanging drywall on wood studs, go with coarse drywall screws. Use self-drilling pan-head screws, which have finer threads than standard drywall screws, if you’re hanging the drywall metal studs.

  • What drywall screw size should I use?

    The size of drywall screws you should use depends on the thickness of the drywall. Use 1-1/4-inch to 1-3/8-inch drywall screws when hanging 1/2-inch drywall. A 1-inch drywall screw is adequate for 1/4-inch drywall. For thicker 5/8-inch panels, you’ll need to use longer 1-3/8-inch or 1-5/8-inch screws.

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Tony Carrick
Tony is a recognized expert in the home and DIY space, as well as outdoor recreation. His articles have appeared on websites such as Bob Vila, U.S. News and World Report, Angi, Popular Science, and Popular Mechanics. He can be emailed at awcarrick@gmail.com. His online portfolio is available at https://www.tonycarrick.com/.

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