Drywall calculator for walls and ceilings
This drywall calculator tells you how many sheets of drywall (gypsum board, plasterboard) you need for the walls and ceiling of a room, plus the screws, joint tape and joint compound to finish them. Enter the room length, width and height, the doors and windows, the sheet size and a waste allowance, and it rounds up to whole sheets.
Use it as a drywall calculator for a room, or set the number of identical rooms to estimate a whole house in one go. Choose feet and inches or metres and millimetres, and sheets of 4 × 8, 4 × 10, 4 × 12 ft, or 1200 × 2400 and 1200 × 3000 mm. It answers the common question “how many sheets of drywall do I need for a 12 × 10 room?” in seconds.
The calculation runs in your browser. It is an estimate for ordering; always check the board type, fire rating and fixing rules for your wall assembly.
How to use the Drywall Calculator
- Pick feet or metres, then enter the room length, width and wall height.
- Tick walls, ceiling or both, and enter how many doors and windows each room has and the area of each.
- Choose the sheet size, one or two layers, and a waste allowance (10% is a sensible start).
- Check the framing spacing and screw spacing, and edit the tape and compound rates if your product says otherwise.
- Read the number of sheets, screws, tape and compound, then copy the summary.
Drywall Calculator features
Walls, ceiling or both
Switch either on or off to cover a ceiling-only job or walls-only job.
Openings handled
Deduct doors and windows, or leave them in as many contractors do for waste.
Five sheet sizes
US 4 × 8, 10 and 12 ft and metric 1200 × 2400 and 3000 mm.
Fixings and finishing
Screws from framing and screw spacing, plus tape and joint compound.
Whole house
Multiply identical rooms, or run the tool room by room and add the sheets.
How many sheets of drywall do I need?
Sheets = (wall area + ceiling area − openings) × layers × (1 + waste) ÷ sheet area, rounded up. A 12 × 10 ft room with 8 ft walls has 2 × (12 + 10) × 8 = 352 ft² of wall and 120 ft² of ceiling. A door (20 ft²) and a window (15 ft²) take off 35 ft², leaving 437 ft². With 10% waste that is 480.7 ft², and a 4 × 8 sheet covers 32 ft², so 15.02 sheets: buy 16.
A quick rule: one 4 × 8 sheet covers 32 ft² (2.97 m²), and one 4 × 12 sheet covers 48 ft². Longer sheets mean fewer joints on ceilings, but they are heavy; for ceilings many people use 4 × 12 where the room allows. For an L-shaped room, calculate each rectangle separately and add the sheets, or measure the odd areas with the area calculator.
Screws, tape and compound
The screw spacings above are the usual values quoted by gypsum board makers for single-layer, non-fire-rated work (checked 19 October 2026). Tape and compound use is a rule of thumb that varies with finish level, product and skill, so both are inputs you can change.
| Item | Default used | Why |
|---|---|---|
| Screws, walls | every 16 in along 16 in framing | Common single-layer spacing for walls |
| Screws, ceiling | every 12 in along framing | Ceilings carry the board weight, so fixings are closer |
| Joint tape | 37 ft per 100 ft² (about 11 m per 9.3 m²) | Rule of thumb for seams and corners |
| Joint compound | 1 US gal per 100 ft² (about 0.4 L/m²) | Rule of thumb for three coats |
Tips and limits
- Fire-rated, moisture-resistant and soundproofed walls follow their tested assembly, which can need closer screws, extra layers and special board. Check the manufacturer's listing.
- Odd-shaped rooms, soffits and stairwell walls add cuts; raise the waste allowance to 15% for those.
- Framing the wall first? The stud calculator counts studs, plates and headers. Insulating it? Try the insulation calculator, and for a suspended ceiling the false ceiling calculator. Paint after finishing: paint calculator.
- Corner bead, trim and fasteners for other trades are not included.
Drywall Calculator FAQ
How many sheets of drywall do I need for a room?
Add the wall area (perimeter × height) and the ceiling area, subtract openings if you like, add 10% waste and divide by the sheet area. A 12 × 10 ft room with 8 ft walls needs about 16 sheets of 4 × 8.
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. A 1200 × 2400 mm sheet is 2.88 m² (31 ft²).
Should I subtract doors and windows?
You can, and this tool does by default. Many contractors skip small openings because the offcuts are rarely reusable; untick the option to see the difference.
How many screws per sheet of drywall?
Roughly 18 to 24 for a 4 × 8 sheet on 16 in framing with screws at 16 in (walls) or 12 in (ceilings). The calculator works from your framing and screw spacing, then adds waste.
How much joint compound do I need?
A common rule is about 1 gallon per 100 ft² of board for three coats, or roughly 0.4 L per m². Heavier finish levels use more, so adjust the rate.
Is this a drywall calculator for the whole house?
Yes. Set the number of identical rooms, or calculate each room and add the sheets. Always round up on the total, not each room, to waste less board.