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Drywall calculator
Give the room size and the sheet length: the number of panels, the screws, the joint tape and the gallons of compound appear together.
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Drywall sheets
17
4 x 8 ft sheets for 492 sq ft of walls and ceiling, plus 10%
| Board installed | 544 sq ft |
| Drywall screws | 1.5 lb |
| Joint tape | 201 ft |
| All-purpose joint compound | 5.4 gal |
Screws, tape and compound scale USG’s figures for 1,000 sq ft of board (2.7 lb, 370 ft, 10 gal) to the board you hang. How this is calculated.
A 12 by 12 foot room with 8 foot walls and a ceiling, one door and one window cut out, needs 17 sheets of 4 by 8 foot drywall once you add a 10% allowance for cuts, or 12 sheets of 4 by 12. That board covers 544 square feet, and the finishing supplies scale from the USG installation guide, which lists 2.7 lb of Type W screws, 370 feet of joint tape and 10 gallons of all-purpose compound for every 1,000 square feet of panels. For this room that means about 1.5 lb of screws, 201 feet of tape and 5.4 gallons of compound. Leave the ceiling out and the walls alone take 12 sheets of 4 by 8. The calculator deducts 21 square feet per door and 15 per window, lets you change the waste allowance and multiplies the sheet count by the price you see in the store.
How the sheet count is built
Drywall is counted the way paint is measured: the four walls (perimeter times height), minus the openings, plus the ceiling if you are covering it. For the 12 by 12 room that is 348 square feet of wall and 144 of ceiling, 492 in all. The calculator adds your allowance, divides by the face of one sheet (32 square feet for 4 by 8, 40 for 4 by 10, 48 for 4 by 12, the three sizes in the USG installation guide) and rounds up. With no allowance at all the room would need 16 sheets; the default 10% brings it to 17.
Why add anything? Each window and door leaves offcuts too oddly shaped to reuse and outlet boxes and corners waste narrow strips. A plain bedroom can get by with less, a bathroom full of pipes and a soffit needs more, which is why the field stays open.
| Room | Area to cover | 4 x 8 sheets | 4 x 12 sheets | Screws | Tape | Compound |
|---|---|---|---|---|---|---|
| 10 x 10 ft, 8 ft walls | 384 sq ft | 14 | 9 | 1.2 lb | 166 ft | 4.5 gal |
| 10 x 12 ft, 8 ft walls | 436 sq ft | 15 | 10 | 1.3 lb | 178 ft | 4.8 gal |
| 12 x 12 ft, 8 ft walls | 492 sq ft | 17 | 12 | 1.5 lb | 201 ft | 5.4 gal |
| 12 x 16 ft, 8 ft walls | 604 sq ft | 21 | 14 | 1.8 lb | 249 ft | 6.7 gal |
| 14 x 20 ft, 9 ft walls | 856 sq ft | 30 | 20 | 2.6 lb | 355 ft | 9.6 gal |
| 20 x 22 ft, 9 ft walls | 1,160 sq ft | 40 | 27 | 3.5 lb | 474 ft | 12.8 gal |
Long sheets or short sheets
Four by twelve panels hide most of the butt joints, the short ends that have no tapered edge and are the hardest seams to make flat. On an 8 foot wall laid horizontally, a 12 foot sheet runs the full length of a 12 foot room in one piece. The catch is weight and access. USG lists its UltraLight 1/2 inch panel at a nominal 1.25 lb per square foot, so a 4 by 8 sheet of it weighs about 40 lb and a 4 by 12 about 60 lb, and standard board is heavier still. A 12 foot sheet will not turn the corner of many stairways, and on a ceiling it usually takes two people or a panel lift. For a 20 by 22 foot garage with 9 foot walls, 4 by 12 board brings the count to 27 panels, where the long sheets cut the number of butt joints to finish.
Thickness and fastening
USG makes gypsum panels in 5/8, 1/2, 3/8 and 1/4 inch, and warns that the 1/4 inch panel is only for covering existing walls and ceilings, never as a single layer. Its guide spaces screws at most 12 inches apart on ceilings and 16 inches on walls, at least 3/8 inch from the ends and edges. Those spacings are where the 2.7 lb per 1,000 square feet comes from. If you nail instead, the same table lists 5.3 lb of nails for 1,000 square feet, cut in half when the board is glued as well.
Tape and compound: the part people underbuy
The 10 gallons per 1,000 square feet that USG gives for all-purpose compound covers the flat joints, inside corners and outside corners finished with metal bead in a typical room. A room with many outside corners, a coffered ceiling or a lot of patching will use more. The calculator scales tape and compound to the board you hang rather than the wall area, so the 10% allowance raises them too; for the 14 by 20 foot room with 9 foot walls in the table, that is 355 feet of tape and 9.6 gallons of compound on 30 sheets. Paper tape comes in rolls, compound in buckets and boxes: round both up to the package on the shelf. Before painting, plan a coat of drywall primer; the paint calculator sizes it with the same room inputs.
Hanging it yourself or hiring out
BLS counted 83,080 drywall and ceiling tile installers in May 2025, with a mean wage of $30.58 an hour and the middle half earning between $22.81 and $35.69. Some owners split the job: they hang the board, which is mostly lifting and screwing, and pay a finisher for the coats of mud and the sanding, the step that shows under paint. When you compare quotes, ask whether they price per sheet or per square foot of board and whether the level of finish is stated in writing.