How to use the drywall calculator
- Choose a sheet size. 4 × 8 ft sheets are easiest to handle; 4 × 10 and 4 × 12 ft sheets mean fewer seams to tape on long walls and ceilings.
- Enter the room length, width and wall height. The calculator works out all four walls from the perimeter.
- Include the ceiling if you’re hanging it too.
- Subtract openings. Each door removes about 21 sq ft (3 × 7 ft) and each window about 15 sq ft (3 × 5 ft). Use Other openings for patio doors, archways or large windows.
- Set the waste allowance. 10% for typical rooms; 15% for rooms with many corners, soffits or sloped ceilings.
How many sheets of drywall: the formula
Net area = wall area + ceiling area − openings
Sheets = net area × (1 + waste %) ÷ sheet area → round up
Joint compound ≈ net area × 0.01 gal · Tape ≈ net area × 0.37 ft · Screws ≈ 1 per sq ft of board
The finishing figures come from gypsum manufacturers’ published estimating guides for taping plus finish coats (USG’s installation guide and Gypsum Construction Handbook): about 10 gallons (roughly 138 lb) of ready-mixed all-purpose compound, 370 ft of paper tape and about 1,000 screws per 1,000 sq ft of board on framing 16 in on center (about 850 at 24 in).
| Sheet | Area | Screws per sheet (≈) |
|---|---|---|
| 4 × 8 ft | 32 sq ft | 32 |
| 4 × 10 ft | 40 sq ft | 40 |
| 4 × 12 ft | 48 sq ft | 48 |
Worked examples
How many sheets of drywall for a 12×12 room?
Walls: 2 × (12 + 12) × 8 = 384 sq ft. Ceiling: 144 sq ft. Minus one door (21) and one window (15) leaves 492 sq ft. With 10% waste that’s 541 sq ft ÷ 32 = 16.9, so 17 sheets of 4 × 8 — or 12 sheets of 4 × 12. You’ll also need about 4.9 gallons of compound (two 4.5 gal pails), one 250 ft roll of tape and about 544 screws.
A 14 × 16 ft family room with 9 ft walls, walls only
Walls: 2 × 30 × 9 = 540 sq ft, minus two doors and two windows (72 sq ft) = 468 sq ft. With 10% waste and 4 × 12 sheets: 11 sheets, about 4.7 gallons of compound and 173 ft of tape.
With 9 ft walls, hanging 4 × 12 sheets horizontally plus a narrow rip at the bottom often gives fewer butt joints than 4 × 8s. Fewer joints means less taping.
Waste factor and buying tips
- Use the right board. ½ in is standard for walls; ceilings typically use ½ in sag-resistant or ⅝ in board. Bathrooms use moisture-resistant board, and some walls (for example between a garage and living space) need fire-rated Type X — check your local code.
- Longer sheets, fewer seams. If you can get them into the room, 4 × 12 sheets reduce butt joints, which are the hardest to finish flat.
- Lightweight compound sands more easily but covers a little less per pail. Setting-type (powder) compound is handy for the first coat on butt joints and repairs.
- Corner bead is extra. Count every outside corner (and window returns) and buy bead by the length.
- Screws: 1¼ in coarse-thread for ½ in board on wood studs, 1⅝ in for ⅝ in board. Use fine-thread screws on metal studs.
- Buy a sheet or two extra — a damaged corner or a mis-cut is common on the first wall.
Laying new floors afterwards? Use the flooring calculator or the tile calculator.
Drywall sheets for common rooms
| Room (8 ft walls, with ceiling) | Net area* | 4 × 8 sheets | 4 × 12 sheets |
|---|---|---|---|
| 10 × 10 ft | 384 sq ft | 14 | 9 |
| 12 × 12 ft | 492 sq ft | 17 | 12 |
| 12 × 14 ft | 548 sq ft | 19 | 13 |
| 14 × 16 ft | 668 sq ft | 23 | 16 |
*One door and one window subtracted; sheets include 10% waste.
Sources & assumptions
How this calculator gets its numbers. Full method: our methodology.
- Board area = wall and ceiling area minus doors (21 sq ft each) and windows (15 sq ft each); sheets are 4×8, 4×10 or 4×12 ft.
- Finishing materials per 1,000 sq ft of board, from USG's estimating tables: about 370 ft of paper tape and about 10 gal (138 lb) of ready-mixed all-purpose compound; screws at about 1 per sq ft on 16 in framing. Check the pail label for your compound.
- Default waste is 10%. Sheets, pails, rolls and screw counts are rounded up.
Sources
- USG, Sheetrock Brand Paper Joint Tape submittal sheet (J1736). Coverage: approx. 370 ft of tape per 1,000 sq ft of gypsum panels; 250 ft rolls.
- USG, Sheetrock Brand Installation and Finishing Guide (J371). Measuring and estimating: deduct large openings, convert square footage to panels, and the fastener, joint compound and tape quantity table.
- USG, Gypsum Construction Handbook. Reference handbook for gypsum board installation and finishing.
Last reviewed . Product figures vary by brand; the label on what you buy wins.
Frequently asked questions
How many sheets of drywall do I need for a 12x12 room?
With 8 ft walls, the ceiling, one door and one window, a 12 × 12 room has about 492 square feet to cover. Adding 10 percent for waste, you need 17 sheets of 4 × 8 drywall or 12 sheets of 4 × 12.
How do I calculate drywall for walls and ceiling?
Add the room length and width, multiply by 2 and by the wall height for the walls, then add length × width for the ceiling. Subtract doors and windows, add 10 percent and divide by the sheet area: 32 square feet for 4 × 8 or 48 for 4 × 12.
How much joint compound do I need?
About 1 gallon per 100 square feet of drywall for taping plus two finish coats, based on manufacturers' estimates of roughly 138 lb of ready-mixed all-purpose compound per 1,000 square feet. A 500 sq ft room needs about two 4.5-gallon pails.
How many screws do I need per sheet of drywall?
Roughly one screw per square foot of board: about 32 for a 4 × 8 sheet. Spacing is typically 12 inches on ceilings and 16 inches on walls along each framing member; follow your local code and the board manufacturer.
How much drywall tape do I need?
About 370 feet of tape per 1,000 square feet of drywall, so a typical 12 × 12 room with ceiling needs a single 250 ft roll.