Materials & quantities
Plasterboard / drywall sheet calculator
Compare sheet orientations and an area estimate for a rectangular wall.
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What a drywall calculator does
A drywall calculator estimates how many sheets of gypsum board (plasterboard) a wall needs. This one compares the two ways to hang a sheet, long edge vertical or long edge horizontal, counts whole sheets on a grid for each, and reports the lower count alongside an area-only estimate.
Common sheets are 4 × 8 ft (32 ft²), 4 × 10 ft (40 ft²) and 4 × 12 ft (48 ft²). The area-only estimate divides the net wall area by the sheet area. The grid count is conservative: it assumes no offcuts are reused, so the number you actually hang usually lands between the two.
In metric, the standard sheet in many markets is 1.2 × 2.4 m (2.88 m²). You can also draw window and door openings on the wall. They reduce the board area, and they appear on the sheet layout, but they do not reduce the grid count, because an opening rarely saves a whole sheet.
How to use the plasterboard / drywall sheet calculator
- Choose Imperial or Metric. Wall and sheet sizes are entered in feet or metres.
- Choose the Surface: Wall, then enter the Wall width and Height; or Ceiling, then enter the Ceiling length and Ceiling width.
- Pick a Sheet size preset (4 × 8, 4 × 10 or 4 × 12 ft; 1200 × 2400, 2700 or 3000 mm) or choose Custom to enter the Sheet length and Sheet width, and set the number of Layers, for example 2 for a double-layer assembly.
- Use Add opening for each window or door: its left offset from the wall corner, sill height above the floor, width and height. Openings must fit within the wall and cannot overlap; ceiling mode ignores them.
- Set a Waste allowance and optional price per sheet. Read the net board area, area-only estimate, conservative grid count, sheets with waste, the lower-count orientation, and the joint tape, joint compound and screw estimates at typical rates. Download the sheet layout as SVG, export a PDF or CSV, or copy the result.
Worked example
Imperial: A 16 × 8 ft wall fits four 4 × 8 ft sheets vertically before waste.
Metric: A 4.8 × 2.4 m wall fits four 1.2 × 2.4 m sheets vertically before waste.
Drywall sheet sizes and coverage
Sheet width in North America is almost always 4 ft, with lengths of 8, 10 and 12 ft (and longer to order). Boards 54 in wide are made for 9 ft walls, so two rows hung horizontally cover the height without a strip. In the UK, Australia and New Zealand, 2400 × 1200 mm is the standard sheet, with longer lengths and 900 mm widths also sold.
1/2 in is the usual board thickness for residential walls. 5/8 in Type X is used where a fire-resistance rating is required, and moisture- or mold-resistant board is used in wet areas. Count each board type separately.
| Sheet | Coverage (ft²) | Coverage (m²) |
|---|---|---|
| 4 × 8 ft | 32 | 2.97 |
| 4 × 10 ft | 40 | 3.72 |
| 4 × 12 ft | 48 | 4.46 |
| 54 in × 12 ft | 54 | 5.02 |
| 1.2 × 2.4 m | 31.0 | 2.88 |
| 1.2 × 2.7 m | 34.9 | 3.24 |
| 1.2 × 3.0 m | 38.8 | 3.60 |
Should drywall be hung horizontally or vertically?
On residential walls up to 8 ft, hanging horizontally usually wins. Two 4 ft rows fill an 8 ft wall, each sheet bridges more studs, and there are fewer feet of joint to tape: a 12 × 8 ft wall hung with two 4 × 12 sheets has one 12 ft seam at a comfortable height, while three vertical 4 × 8 sheets leave two 8 ft seams.
Vertical hanging is common on commercial steel framing, where every long edge lands on a stud, and where the wall height matches a sheet length, such as 4 × 10 sheets on a 10 ft wall. In metric, a 3.6 × 2.7 m wall takes three 1.2 × 2.7 m sheets vertically, but six 1.2 × 2.4 m sheets on a grid because of the 0.3 m strip. Fire-rated and acoustic assemblies may require a particular orientation and fastening, so follow the listed design.
The table shows the calculator's grid count for common 8 ft walls, which is how it picks the lower-count orientation.
| Wall length | 4 × 8 vertical | 4 × 8 horizontal | 4 × 12 horizontal | Area-only (4 × 8) |
|---|---|---|---|---|
| 10 ft | 3 | 4 | 2 | 3 |
| 12 ft | 3 | 4 | 2 | 3 |
| 14 ft | 4 | 4 | 4 | 4 |
| 16 ft | 4 | 4 | 4 | 4 |
| 20 ft | 5 | 6 | 4 | 5 |
How many sheets of drywall for a 12x14 room?
A 12 × 14 ft room with 8 ft walls has 416 ft² of wall and a 168 ft² ceiling, 584 ft² in total. Divided by 48 ft², that is 12.2 sheets of 4 × 12, the absolute minimum with perfect offcut reuse. Run each surface through the calculator and the conservative grid gives 16 sheets before waste.
The ceiling is entered as a 14 × 12 ft rectangle. Hung across the 12 ft direction, four 4 × 12 sheets cover it, with the last one ripped to 2 ft. A standard 3 ft × 6 ft 8 in door reduces board area by 20 ft² but does not change the grid count.
For an area check across many rooms, the floor and wall area calculator totals walls from a room list.
| Surface | Size | Area | Area-only sheets | Grid sheets |
|---|---|---|---|---|
| Long wall | 14 × 8 ft | 112 ft² | 3 | 4 |
| Long wall | 14 × 8 ft | 112 ft² | 3 | 4 |
| Short wall | 12 × 8 ft | 96 ft² | 2 | 2 |
| Short wall | 12 × 8 ft | 96 ft² | 2 | 2 |
| Ceiling | 14 × 12 ft | 168 ft² | 4 | 4 |
| Total | 584 ft² | 14 | 16 |
Who it is for and when to use it
Room renovations
Count sheets wall by wall for a remodel, with windows and doors drawn in place so the layout shows where the cuts fall.
Basement and attic finishing
Compare 4 × 8 and 4 × 12 sheets, or 54 in board on taller walls, before choosing what fits down the stairs and what hangs with the fewest seams.
Estimating for bids
Produce a per-wall sheet count and cost, and export the inputs, method and results as a PDF or CSV for the estimate file.
Double-layer fire and acoustic walls
Set Layers to 2 for assemblies that call for two layers of board. The board type and fastening still come from the listed assembly.
Method, formulas & assumptions
Grid count = ceil(face width ÷ sheet width) × ceil(face height ÷ sheet length) for a wall or ceiling, comparing both orientations. Openings reduce the area estimate, not the conservative grid count. Tape, compound and screws use typical per-area estimating rates.
Imperial inputs are converted with exact factors (1 ft = 0.3048 m, 1 lb = 0.45359237 kg, 1 US gal = 3.785411784 L) before the calculation runs in SI, then results are converted back.
Common mistakes to avoid
- Ordering by total area alone for a room with many short walls, returns and openings. Offcuts rarely fit where you need them.
- Forgetting the second layer on a two-layer fire-rated or acoustic assembly.
- Using 4 × 8 sheets on a 9 ft wall, which leaves a full extra row of 1 ft strips and more joints to finish.
- Assuming a window or door saves whole sheets. The board around an opening is usually cut from full sheets.
- Letting sheet ends fall between studs or joists. Plan the layout so butt ends land on framing.
- Counting all board as one type. Moisture-resistant board for wet areas and Type X for rated walls and ceilings need their own counts.
Scope & limits
One rectangular wall or ceiling face. Openings do not automatically save whole sheets. Finishing rates are typical estimating figures, not a specification. Framing, fire and acoustic systems need separate design.
Frequently asked questions
How many sheets of drywall do I need for a 12x12 room?
A 12 × 12 ft room with 8 ft walls has 384 square feet of wall and a 144 square foot ceiling, 528 square feet in total. By area that is 17 sheets of 4 × 8 or 11 sheets of 4 × 12 before waste; a grid count per wall will be higher.
How many square feet are in a sheet of drywall?
A 4 × 8 ft sheet covers 32 square feet, a 4 × 10 ft sheet 40 square feet and a 4 × 12 ft sheet 48 square feet.
Is it better to hang drywall horizontally or vertically?
On residential walls up to 8 ft, horizontal hanging usually means fewer and shorter seams. Vertical hanging suits steel framing and walls whose height matches a sheet length, and some fire-rated assemblies specify the orientation.
How much extra drywall should I buy?
A 10% allowance is a common starting point and is the calculator's default. Rooms with many openings, short walls or angled ceilings need more.
What size is a sheet of plasterboard?
The standard plasterboard sheet in the UK, Australia and New Zealand is 2400 × 1200 mm, which covers 2.88 square metres. Longer sheets and 900 mm widths are also sold.
What drywall is required in a garage?
The 2021 IRC Table R302.6 calls for at least 1/2 in gypsum board on the garage side of walls separating the garage from the house, and at least 5/8 in Type X on the garage ceiling where there are habitable rooms above. Confirm the requirement with your adopted code.
Do windows and doors reduce the number of sheets?
They reduce the board area in the calculator, but not the conservative grid count, because the board around an opening is normally cut from full sheets.
Do I need an account to download the result?
No. All calculations, local file processing and exports on this page are free, without an account.
Where are my inputs stored?
The tool keeps inputs in this browser tab. It does not upload them or create a cloud copy. Save or download anything you want to keep before leaving the page. Standard site analytics may operate independently of the tool.
Can I work in metric instead of imperial?
Yes. Use the Imperial / Metric switch above the inputs. Imperial (feet, inches, pounds, gallons) is the default; switching converts every dimensional field and result, and your choice is remembered across the free tools in this browser.
Further reading
- Fire-rated wall assemblies explained
- STC sound ratings for walls
- Wall build-ups template
- All materials & quantities tools
- All free architecture & construction tools
- Harth resource library
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