Drywall Calculator
- Updated
- Imperial and metric
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Results
14 sheets of 4 × 8 ft drywall for 383 ft²
Compound, tape and screw figures are typical rules of thumb. Actual use varies with the finish level, the board layout and your technique.
How to use the drywall calculator
- Choose how to measure the walls. Room size uses the room's length, width and wall height. Total wall length suits a single wall, a partial room or a basement where only some walls get board.
- Decide whether to include the ceiling. With room size, the ceiling is the room length × width.
- Enter the number of doors and windows. The default sizes are 3 × 7 ft for a door and 3 × 4 ft for a window; change them for patio doors or large windows.
- Pick the sheet size and a waste allowance. The default is 10%.
- Check the typical rates for compound, tape and screws, and add prices if you want a cost estimate.
Drywall formula
Ceiling area = Room length × Room width
Sheets = Area × (1 + Waste %) ÷ Area of one sheet, rounded up
Compound ≈ Board area × 0.0094 gal per ft² (0.38 L per m²)
Tape ≈ Board area × 0.37 ft per ft² (1.2 m per m²)
A 4 × 8 ft sheet covers 32 ft², a 4 × 10 ft sheet 40 ft² and a 4 × 12 ft sheet 48 ft². A metric 1200 × 2400 mm sheet covers 2.88 m². The calculator rounds walls and ceiling up separately, because they are cut and hung as separate jobs and offcuts rarely move between them.
Worked example: a 12 × 14 ft bedroom
The room has 8 ft walls, one door and two windows, and the ceiling is being boarded too. The walls are 2 × (12 + 14) × 8 = 416 ft². Taking off the door (21 ft²) and two windows (24 ft²) leaves 371 ft². With 10% waste, the walls need 408.1 ÷ 32 = 12.75, so 13 sheets of 4 × 8. The 168 ft² ceiling needs 6 more, for 19 sheets in total.
Finishing 539 ft² of board takes about 5.1 gallons of joint compound (2 buckets of 4.5 gal), about 199 ft of paper tape (1 roll of 250 ft) and roughly 656 screws.
Drywall sheets for common room sizes
Rooms with 8 ft walls, one 3 × 7 ft door, one 3 × 4 ft window and 10% waste. Wall area is after the openings.
| Room | Wall area | 4 × 8 sheets: walls / with ceiling | 4 × 12 sheets: walls / with ceiling |
|---|---|---|---|
| 10 × 10 ft | 287 ft² | 10 / 14 | 7 / 10 |
| 10 × 12 ft | 319 ft² | 11 / 16 | 8 / 11 |
| 12 × 12 ft | 351 ft² | 13 / 18 | 9 / 13 |
| 12 × 14 ft | 383 ft² | 14 / 20 | 9 / 13 |
| 12 × 16 ft | 415 ft² | 15 / 22 | 10 / 15 |
| 14 × 16 ft | 447 ft² | 16 / 24 | 11 / 17 |
| 16 × 20 ft | 543 ft² | 19 / 30 | 13 / 21 |
Mud, tape and screws: rules of thumb
Finishing materials depend on the level of finish, the board layout and the person doing the work, so the calculator uses typical figures that you can change:
- Joint compound: about 9.4 gallons per 1,000 ft² of board, or roughly 1 gallon per 100–110 ft² (0.38 L per m²). That covers taping plus two finish coats over joints and screw heads. A skim coat over the whole surface uses much more.
- Paper tape: about 370 ft per 1,000 ft² of board (1.2 m per m²). Corner bead for outside corners is extra.
- Screws: about 32 per 4 × 8 sheet on walls, where screws are typically up to 16 inches apart along each stud, and about 40 on ceilings, where spacing is closer, typically 12 inches. Your local code and the board manufacturer's instructions set the actual fastening schedule.
| Sheet size | Coverage | Typical screws: walls / ceiling |
|---|---|---|
| 4 × 8 ft | 32 ft² (2.97 m²) | 32 / 40 |
| 4 × 10 ft | 40 ft² (3.72 m²) | 40 / 50 |
| 4 × 12 ft | 48 ft² (4.46 m²) | 48 / 60 |
| 1200 × 2400 mm | 2.88 m² (31 ft²) | 31 / 39 |
| 1200 × 2700 mm | 3.24 m² (34.9 ft²) | 35 / 44 |
| 1200 × 3000 mm | 3.6 m² (38.8 ft²) | 39 / 49 |
Tips for buying drywall
- Use longer sheets on long walls. A 12 ft sheet covers a 12 ft wall with no butt joint, and butt joints (where two uncut ends meet) are the hardest to finish flat. Long sheets are heavy, though, so plan on two people, or a drywall lift for ceilings.
- Raise the waste for awkward rooms. Offcuts around doors, windows and corners are often too small to reuse. For rooms with many openings, angles or short walls, 15% is a safer allowance than 10%.
- Use the right board for the room. Damp rooms such as bathrooms usually call for moisture-resistant board, and shower walls that will be tiled need a cement board or another tile backer. Some walls and ceilings, such as those next to an attached garage, may need fire-rated board. Your local code says where.
- Check the labels. Bucket sizes and tape roll lengths vary by brand, so enter the figures from the products you buy.
- Plan the floor and tile next. Once the walls are done, size the flooring with the flooring calculator or a tiled floor or backsplash with the tile calculator.
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 are 351 sq ft after the openings. With 10% waste that is 13 sheets of 4 × 8 drywall. The 144 sq ft ceiling takes 5 more, for 18 in total. In 4 × 12 sheets it is 9 for the walls and 4 for the ceiling.
How much joint compound and tape do I need?
A common rule of thumb is about 9.4 gallons of compound and 370 feet of paper tape per 1,000 sq ft of drywall, enough for taping plus two finish coats. That is roughly 1 gallon per 100–110 sq ft (about 0.38 L per m²). For 1,000 sq ft you would buy three 4.5-gallon buckets and two 250 ft rolls of tape. A skim coat over the whole surface uses much more.
How many screws do I need per sheet of drywall?
About 32 per 4 × 8 sheet on walls, where screws are typically up to 16 inches apart along each stud, and about 40 on ceilings, where they are typically 12 inches apart. Bigger sheets need more in proportion, such as about 48 for a 4 × 12 sheet on a wall. Your local code and the board manufacturer set the actual spacing.
Should I subtract doors and windows when estimating drywall?
Yes, subtract them so you do not buy sheets you will not hang. The calculator uses 3 × 7 ft for a door and 3 × 4 ft for a window by default; enter your own sizes for patio doors and large windows. Offcuts around openings are often too small to reuse, so keep a waste allowance of at least 10%.
Is it better to use 4×8 or 4×12 drywall sheets?
Longer sheets cover more wall with fewer butt joints, the end joints that are hardest to finish, so 4 × 12 sheets usually mean less taping on long walls. They are heavy and awkward, need two people to hang and may not fit up stairs or through doorways. 4 × 8 sheets are easier to carry and transport, which is why many DIYers choose them.