Drywall Calculator
Sheets of drywall for a room's walls and ceiling less doors and windows, in 4x8, 4x12 or 1200x2400, with screws, joint tape and joint compound estimates.
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About this toolWhat is the Drywall Calculator?
Hanging drywall starts with a sheet count: the area of the walls and ceiling, less the doors and windows, divided by the area of a sheet, plus waste for cut-offs. Finishing it needs screws, joint tape and joint compound, which all scale with the board area. This calculator does both from the room dimensions.
Enter the room length, width and wall height in feet and inches or metres, how many rooms of that size, and whether to include the ceiling. Add the doors and windows and any extra area such as a closet. Choose the sheet size, from 4x8 to 54 in x 12 ft or 1200 x 2400 mm, and the waste.
You get the sheets to buy, the net and purchased board area, and estimates of screws, tape and compound with the pails and rolls to buy. The estimating rates are typical published figures and are editable, so you can match your own crew or product.
- Walls, ceiling, openings, extra area and multiple identical rooms
- Sheet sizes from 4x8 to 54 in x 12 ft and 1200 x 2400 to 3000 mm
- Editable screw, tape and compound rates with pails and rolls
- Board cost, imperial and metric with feet-inch input
- Copy results and share a link with your inputs
How to use the Drywall Calculator
- Choose imperial or metric and enter the room length, width and wall height. Set how many identical rooms there are.
- Tick the ceiling if it is being boarded too.
- Enter the number and size of doors and windows, and any extra area per room for closets, soffits or bulkheads.
- Pick the sheet size and waste percentage.
- Read the sheets, screws, tape and compound, adjust the rates if your product differs, and copy the list.
Worked examples
14 x 12 ft bedroom with ceiling
Input
14 x 12 ft, 8 ft walls, ceiling, one 36 x 80 in door, two 36 x 48 in windows, 4x8 sheets, 10% waste
Output
19 sheets, 540 ft² net, about 608 screws, 200 ft of tape, 5.1 gal of compound
Walls are 416 ft² and the ceiling 168 ft²; the openings take off 44 ft². 540 / 32 x 1.1 = 18.6, so 19 sheets.
Same room with 12 ft sheets
Input
4 x 12 ft sheets, other inputs unchanged
Output
13 sheets, about 624 screws
Fewer, longer sheets mean fewer butt joints to finish. Board area bought is slightly higher, so screws rise a little.
Metric room
Input
4 x 3.5 m, 2.5 m walls, ceiling, 900 x 2100 door, 1200 x 1200 window, 1200 x 2400 sheets, 10% waste
Output
19 sheets, 48.2 m² net, about 58 m of tape and 18.4 L of compound
Each 1200 x 2400 sheet covers 2.88 m², slightly less than a 4x8.
Background and insight
Wall area is the room perimeter times the height; the ceiling is length times width. Openings come off the total, and a waste allowance of 10 to 15% covers cut-offs at doors, windows and corners. Longer sheets reduce the number of butt joints, which are the hardest to finish, so a 12 ft room is often hung with 12 ft sheets even though the sheet count barely changes.
For finishing materials the calculator uses typical rates and labels them as such: about 32 screws per 4x8 sheet (one per square foot, from screws at 12 in centres on ceilings and 16 in on walls per GA-216 and the board makers' instructions), about 370 ft of paper tape per 1,000 square feet of board (USG's published coverage), and about 9.4 gallons of ready-mixed all-purpose compound per 1,000 square feet for taping and three coats. Lightweight and setting compounds cover differently, so edit the rate to suit.
Common use cases
Ordering board for a renovation
Count sheets per room and add rooms of the same size before calling the supplier.
Basement finishing
Estimate walls only, with tall or short sheets, for a basement with exposed or dropped ceilings.
Planning finishing labour
Use tape and compound quantities to plan coats and buckets for a taping crew.
Comparing sheet sizes
See how 4x8, 4x12 and 54 in sheets change the count and the number of joints.
Tips and limitations
- Hang the ceiling first, then the walls with sheets running horizontally so the top sheet supports the ceiling edge.
- Use moisture-resistant board in bathrooms and fire-rated Type X where the code calls for it, for example between a garage and the house.
- Do not subtract small windows; the offcuts rarely fit elsewhere.
- Corner bead, primer, adhesive and setting compound for the first coat are not included.
- Ceilings framed at 24 in centres often call for 5/8 in board or a sag-resistant 1/2 in product, especially under a water-based texture.
Frequently asked questions
How many sheets of drywall do I need for a 12x12 room?
With 8 ft walls and a ceiling, the area is 384 + 144 = 528 square feet, or 16.5 sheets of 4x8 before openings and waste. With 10% waste and a door and window removed, plan on about 17 to 18 sheets.
How many screws per sheet of drywall?
About 32 for a 4x8 sheet, roughly one per square foot. That comes from screws every 12 in on ceilings and 16 in on walls along each framing member. A 4x12 sheet takes about 48.
How much joint compound do I need?
About 9 to 10 gallons of ready-mixed all-purpose compound per 1,000 square feet of board for taping and finishing coats. A 4.5 gallon pail does roughly 450 to 500 square feet.
How much drywall tape do I need?
About 370 ft of paper tape per 1,000 square feet of drywall, the coverage USG publishes. A 500 ft roll covers roughly 1,350 square feet.
Should I subtract doors and windows from the drywall area?
Subtract doors and large windows. Small windows usually do not save a sheet because the cutout is waste anyway, so many estimators leave them in.
What size drywall sheet should I use?
The longest size you can carry and fit into the room. 4x12 sheets on a 12 ft wall leave no butt joints. 54 in wide board suits 9 ft walls with two rows, and 4x8 is easiest to handle alone.
Is there an in-depth guide to the Drywall Calculator?
Yes. “How Much Drywall, Mud and Tape? Estimating a Room” covers the background, how it works, common pitfalls and worked examples. Read the full guide.
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