Drywall calculator
Count the drywall sheets for walls and ceilings, minus doors and windows, plus the screws, tape and joint compound to finish them.
Floor to ceiling.
Sheets to buy
- Sheets to buy
- 184 × 8 ft sheets: 13 for walls, 5 for the ceiling
- Area to cover
- 496 sq ftWalls 352 sq ft, ceiling 144 sq ft, after taking off 32 sq ft of doors and windows. Waste not included.
- Screws
- 466About 30 per sheet
- Joint tape
- 184 ftRolls of 250 ft: 1
- Joint compound
- 4.96 galPacks of 4.5 gal: 2
Waste, door and window sizes
Extra for cuts and breakage. 10% is a starting point, not a rule.
Screws, tape and compound rates
The starting values come from the manufacturer documents listed under Sources. If your products give different figures, use theirs.
Leave empty to skip the pack count.
Leave empty to skip the pack count.
Estimate only. Check product labels and local building rules before you buy or build.
Quick answer
Add the wall area (room perimeter × wall height) and the ceiling area, take off doors and windows, add a waste allowance and divide by the area of one sheet: a 4 × 8 ft sheet covers 32 sq ft. A 12 × 12 ft room with 8 ft walls, one door and one window is 496 sq ft, which with 10% waste is 18 sheets of 4 × 8 drywall, 13 for the walls and 5 for the ceiling.
How to use the drywall calculator
- Choose Room size to type the length, width and wall height of a room, or Areas to type wall and ceiling areas you measured yourself.
- Pick what you are covering: walls and ceiling, walls only or ceiling only, and enter how many doors and windows the walls have.
- Choose the sheet size you plan to buy. The number of sheets, the area to cover, screws, tape and joint compound update as you type.
- Open Waste, door and window sizes to change the 10% waste allowance or the size of your openings. Open Screws, tape and compound rates to use the figures printed on your own products.
How do you calculate how much drywall you need?
Work out the area to cover, add a waste allowance, and divide by the area of one sheet. The wall area of a rectangular room is its perimeter times the wall height; the ceiling is length times width. Doors and windows come off the wall area because no board goes there.
Walls and ceiling are rounded up to whole sheets separately, because off-cuts from wall sheets rarely fit the ceiling. Screws, tape and compound are worked out from the area you cover, before waste, using the rates per 1,000 sq ft that USG publishes for its products.
wall area = 2 × (length + width) × wall height − doors − windowsceiling area = length × widthsheets = area × (1 + waste %) ÷ area of one sheet, rounded upscrews = wall area × 875 ÷ 1,000 + ceiling area × 1,094 ÷ 1,000joint tape (ft) = area × 370 ÷ 1,000joint compound (gal) = area × 10 ÷ 1,000What size drywall sheets can you buy?
Drywall comes 4 ft wide in lengths from 8 to 16 ft, and some panels also come 54 in wide, according to USG product data. The coverage below is worked out from those sizes. Fire-rated walls, such as one between a garage and the house, need the board type and fastening your local code requires.
| Sheet | Area per sheet | Sheets per 1,000 sq ft |
|---|---|---|
| 4 × 8 ft | 32 sq ft | 31.3 |
| 4 × 10 ft | 40 sq ft | 25.0 |
| 4 × 12 ft | 48 sq ft | 20.8 |
| 54 in × 12 ft | 54 sq ft | 18.5 |
Worked examples
Walls and ceiling of a 12 × 12 ft bedroom
The room is 12 × 12 ft with 8 ft walls, one 36 × 80 in door and one 36 × 48 in window. The walls are 2 × (12 + 12) × 8 = 384 sq ft. The door takes off 20 sq ft and the window 12 sq ft, leaving 352 sq ft. The ceiling is 144 sq ft, so the area to cover is 496 sq ft.
With 10% waste, the walls need 352 × 1.1 ÷ 32 = 12.1, so 13 sheets of 4 × 8, and the ceiling 144 × 1.1 ÷ 32 = 4.95, so 5 sheets: 18 sheets in all. At USG’s rates that is 466 screws (about 30 per sheet), 184 ft of tape, one 250 ft roll, and 4.96 gal of joint compound, two 4.5 gal pails.
Basement walls with 9 ft ceilings: 4 × 12 or 54 in sheets
A basement room is 16 × 14 ft with 9 ft walls, two doors (36 × 80 in) and two windows (36 × 48 in), and only the walls get drywall. The walls are 2 × (16 + 14) × 9 = 540 sq ft, less 40 sq ft of doors and 24 sq ft of windows: 476 sq ft.
With 10% waste that is 523.6 sq ft. In 4 × 12 ft sheets (48 sq ft) you need 523.6 ÷ 48 = 10.9, so 11 sheets. In 54 in × 12 ft sheets (54 sq ft) you need 523.6 ÷ 54 = 9.7, so 10 sheets, and two of them hung horizontally cover the 9 ft height exactly. At the default rates, which are USG’s figures for 4 × 8 sheets, the job takes about 417 screws (USG gives slightly lower counts for 4 × 12 ft sheets), 177 ft of tape and 4.76 gal of compound.
How many screws per sheet of drywall?
A 4 × 8 sheet on framing 16 in on center takes about 28 screws on a wall and 35 on a ceiling. USG’s maximum screw spacing over wood framing is 16 in on walls and 12 in on ceilings; the table turns its screw usage figures per 1,000 sq ft into screws per sheet.
| Framing spacing | Screw spacing | Screws per 1,000 sq ft | Screws per 4 × 8 sheet |
|---|---|---|---|
| 16 in | 12 in (ceilings) | 1,094 | 35 |
| 16 in | 16 in (walls) | 875 | 28 |
| 24 in | 12 in (ceilings) | 781 | 25 |
| 24 in | 16 in (walls) | 625 | 20 |
USG adds that an allowance should be made for loss, so buy a few more than the count.
How much joint compound and tape do you need?
Plan on about 10 gal of ready-mixed all-purpose joint compound and 370 ft of paper joint tape per 1,000 sq ft of drywall, the coverage USG gives for those products. A 4.5 gal pail therefore finishes about 450 sq ft, and a 250 ft roll of tape about 676 sq ft.
These are averages for taping, filling and finishing flat joints. Lightweight compounds, setting-type powders and skim coats use different amounts, so if your product label gives its own coverage, type it into the rates and the calculator will use it.
Questions
How many sheets of drywall do I need for a 12×12 room?
A 12 × 12 ft room with 8 ft walls, one door and one window needs 18 sheets of 4 × 8 ft drywall for the walls and ceiling, including 10% for waste: 13 for the walls and 5 for the ceiling. Walls alone take 13 sheets. With 4 × 12 ft sheets the same room takes 13 sheets, 9 for the walls and 4 for the ceiling.
How many screws do I need per sheet of drywall?
About 28 screws per 4 × 8 sheet on a wall and 35 on a ceiling, when the framing is 16 in on center and the screws are 16 in apart on walls and 12 in apart on ceilings, the widest spacing USG gives for wood framing. On framing 24 in on center the same spacing takes about 20 and 25 screws. Closer spacing takes more, and USG says to allow for loss, so buy a few extra.
How much joint compound do I need for drywall?
About 10 gal of ready-mixed all-purpose joint compound per 1,000 sq ft of drywall, according to USG’s product data. One 4.5 gal pail finishes about 450 sq ft, so the walls and ceiling of a 12 × 12 ft room (496 sq ft) take two pails. Lightweight compounds and textures use different amounts, so check the label of the one you buy.
How much drywall tape do I need?
About 370 ft of paper joint tape per 1,000 sq ft of drywall, based on USG’s paper tape data. A 250 ft roll covers about 676 sq ft of board, so one roll is enough for the walls and ceiling of a 12 × 12 ft room, which use 184 ft. Larger rooms and many inside corners call for a second roll.
What size do drywall sheets come in?
Standard drywall is 4 ft wide and 8 to 16 ft long, and some panels also come 54 in wide, according to USG’s data for its 1/2 in UltraLight panels. A 4 × 8 sheet covers 32 sq ft, a 4 × 10 covers 40 sq ft and a 4 × 12 covers 48 sq ft. Longer sheets leave fewer joints to finish but are heavier to lift.
Can I use 1/2 inch drywall on a ceiling?
Yes, if the panel is rated for ceilings. USG lists its 1/2 in UltraLight panels for ceiling framing up to 24 in on center, hung parallel or perpendicular to the joists; under a water-based texture, the unsupported insulation above may weigh no more than 2.2 lb per sq ft. Other boards have their own limits, so check the data sheet of the one you buy.
Sources
- USG, USG Sheetrock Brand UltraLight Panels, submittal sheet WB2501 (checked October 19, 2026)Widths 4 ft and 54 in, lengths 8 to 16 ft; maximum screw spacing 12 in on ceilings and 16 in on walls over wood framing; ceiling framing up to 24 in on center.
- USG, USG Sheetrock Brand All Purpose Joint Compound, submittal sheet J1969 (checked October 19, 2026)Coverage approximately 10 gal per 1,000 sq ft; 4.5 gal pail, 3.5 gal and 4.5 gal cartons.
- USG, USG Sheetrock Brand Paper Joint Tape, submittal sheet J1736 (checked October 19, 2026)Coverage approximately 370 ft per 1,000 sq ft; rolls of 75, 250 and 500 ft.
- USG, The Gypsum Construction Handbook, Appendix: Gypsum Board Screw Usage (scanned copy hosted by InspectApedia) (checked October 19, 2026)Screws per 1,000 sq ft by framing spacing, screw spacing and board size.
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