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Drywall calculator

Enter the room's size and ceiling height, choose 4×8 or 4×12 sheets, and take away doors and windows. You get the number of sheets with waste included, plus the screws, joint compound and tape to finish them.

What are you covering?
Units

Doors and windows

Taken off the wall area. Sizes start at a standard interior door (36 × 80 in) and a 3 × 4 ft window: change them to match yours.

Sheet size
Extra for waste and cuts
Stud and joist spacing
Drywall sheets to buy
18 sheets
4 × 8 ft sheets with 10% extra, for 496 sq ft of walls and ceiling

Sheets

Walls
13
Ceiling
5
Total 4 × 8 ft sheets
18

Walls and ceiling are rounded up separately, since you cut them from different sheets.

Area to cover

Walls
384 sq ft
Less doors and windows
−32 sq ft
Ceiling
144 sq ft
Board to hang
496 sq ft

Finishing supplies (estimates)

Drywall screwsabout 28 per sheet on walls, 35 per sheet on the ceiling
539
Joint compound4.5 gal pails · 4.7 gal (18 L) of ready-mixed
2 pails
Paper joint tape250 ft rolls · 184 ft (56 m) in all
1 roll

Approximate, from USG's published rates: screws 16 in apart on walls and 12 in on ceilings, about 9.4 gal of all-purpose compound and 370 ft of tape per 1,000 sq ft of board. Check the coverage on your bucket.

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How to work out how much drywall you need

  1. 1

    Enter the room's length, width and ceiling height. Turn off walls or ceiling if you only need one of them.

  2. 2

    Enter how many doors and windows there are. Sizes start at a standard 36 × 80 in door and a 3 × 4 ft window; change them to match yours.

  3. 3

    Choose the sheet size and the waste allowance: 10% for a plain room, 15% or more with lots of corners, soffits or angles.

  4. 4

    Read the number of sheets, plus the screws, joint compound and tape to finish them. Add a price per sheet to see the cost.

Features

  • Walls, ceiling or both

    Walls and ceiling are counted and rounded up separately, the way they are cut and hung.

  • Doors and windows

    Enter how many of each with their real sizes, and the openings come off the wall area.

  • Screws, mud and tape

    Estimates from USG's published fastener spacing and coverage rates, in pails and rolls you can buy.

  • Sheet cost

    Enter the price of one sheet to see what the board for the room costs before tax and delivery.

How the estimate works

The wall area is the distance around the room times the ceiling height: 2 × (length + width) × height. Doors and windows come off that, and the ceiling is simply length × width. Each area is then multiplied by your waste allowance, divided by the area of one sheet and rounded up. Walls and ceiling are rounded up separately, since an offcut from the ceiling seldom fits a wall.

For a 12 × 12 ft bedroom with 8 ft walls, one door and one window: the walls are 2 × (12 + 12) × 8 = 384 sq ft, minus 20 sq ft for the door and 12 sq ft for the window, leaving 352 sq ft. The ceiling adds 144 sq ft. With 10% extra that comes to 13 + 5 = 18 sheets of 4 × 8.

More worked examples

  • Family room, 14 × 20 ft with 9 ft walls, two doors and three windows, walls only, 4 × 12 sheets and 10% extra: 536 sq ft of wall, so 13 sheets, about 520 screws and 2 pails of compound.
  • Two-car garage ceiling, 24 × 24 ft, 4 × 12 sheets on joists 24 in apart, with 15% extra for working overhead: 576 sq ft, so 14 sheets and about 490 screws.

Drywall sheet sizes

SheetCoversScrews per sheet (walls · ceiling)
4 × 8 ft32 sq ft28 · 35
4 × 10 ft40 sq ft34 · 43
4 × 12 ft48 sq ft40 · 50

Screw counts assume sheets hung horizontally across framing 16 in on center, with screws 16 in apart on walls and 12 in apart on ceilings, which is the method behind USG's own screw-usage tables. Wider framing takes fewer screws. Sheets 54 in wide are also sold for 9 ft walls, and 1/2 in thick board is the common choice for walls.

Finishing supplies, as rules of thumb

  • Screws: 1-1/4 in coarse-thread drywall screws are the usual choice for 1/2 in board on wood studs; steel studs take fine-thread screws. Expect roughly one screw per square foot of board.
  • Joint compound: about 9.4 gallons of ready-mixed all-purpose compound per 1,000 sq ft, enough for taping and the usual follow-up coats. USG says about two 4.5-gallon pails of its lightweight compound finish 1,000 sq ft.
  • Paper tape: about 370 feet per 1,000 sq ft of board. Rolls are commonly 250 or 500 ft long.

These are approximate figures from USG's published product data. Coverage varies with the compound, how many coats you apply and how smooth a finish you want, so check the bucket and buy a little more rather than run out halfway through a coat.

Before you hang

Measure the room with the square footage calculator if it isn't a simple rectangle, and add the walls of closets as their own room. Finishing a basement or converting a garage? Size the heating and cooling for the new room with the BTU calculator, and if the project includes a new slab, the concrete calculator works out the yards to order.

Frequently asked questions

How many sheets of drywall do I need for a 12 × 12 room?

With 8 ft walls, one door and one window, the walls take 352 sq ft of board and the ceiling 144 sq ft. With 10% extra that is 13 sheets of 4 × 8 for the walls and 5 for the ceiling: 18 sheets in all.

How many square feet is a sheet of drywall?

A 4 × 8 ft sheet covers 32 square feet, a 4 × 10 covers 40 and a 4 × 12 covers 48. Divide the area to cover by the sheet's square footage, add your waste allowance and round up.

How many screws do I need per sheet of drywall?

USG spaces screws 16 in apart on walls and 12 in apart on ceilings when the framing is 16 in on center. A 4 × 8 sheet hung across the studs then takes about 28 screws on a wall and 35 on a ceiling, or roughly one screw per square foot. Buy a few extra for misses.

How much joint compound and tape do I need?

USG's coverage figures work out to about 9.4 gallons of ready-mixed all-purpose compound and 370 feet of paper tape per 1,000 square feet of board. The 12 × 12 bedroom above (496 sq ft) needs about 4.7 gallons of compound and 184 feet of tape.

Should I use 4 × 8 or 4 × 12 sheets?

Longer sheets mean fewer end joints, which are the hardest seams to finish, so 4 × 12 sheets save taping on long walls and ceilings. They are also heavier and harder to carry up stairs or fit in a car. Many DIYers use 4 × 8 sheets for small rooms and walls up to 8 ft long.

Should I subtract doors and windows?

This calculator does, because it gives the board you actually hang. Many pros hang sheets right over small openings and cut them out afterward, so a single window rarely saves a whole sheet; large openings such as patio doors and garage doors do. The waste allowance covers the cut-outs either way.

What thickness of drywall should I use?

In homes, 1/2 inch is the usual thickness for walls and most ceilings. 5/8 inch board is stiffer and is often used on ceilings, especially with framing 24 inches apart, and fire-rated Type X board is required in some places, such as the ceiling of a garage with rooms above it. Check your local building code.

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