Measuring rooms and openings
A room is four walls and, if it gets drywall too, a ceiling. Enter its length, its width and the height of its walls; a single wall takes its length and its height. Doors and windows are areas with no drywall on them: add each, or one line for several of a size.
Worked example. A room 12 × 14 ft with 8 ft walls, one door of 3 × 7 ft, two windows of 3 × 4 ft, ceiling included.
- Walls: 52 ft of wall × 8 ft = 416 sq ft, less 45 sq ft of openings = 371 sq ft
- Ceiling: 12 ft × 14 ft = 168 sq ft
- To cover: 539 sq ft
- Sheets of 4 × 8, with 10% extra: 19
- Screws: about 540. Joint compound: 4.85 gal, so 2 pails
Some hangers do not subtract a door or a small window at all, since the piece cut out of it is rarely used again. To count that way, leave the openings out.
Which sheet size?
A sheet is 4 ft wide, and 8, 10 or 12 ft long: 32, 40 or 48 sq ft. Longer sheets mean fewer joints to tape. The room above takes 19 sheets of 4 × 8, 16 of 4 × 10 or 13 of 4 × 12.
They are also heavier, harder to turn on a stair, and not every store delivers them. Thickness is your choice to make at the store, and your code’s where it asks for a fire-rated board, as between a house and its garage: the count is the same.
Waste and layout
The calculator adds 10% for the cuts, and counts the walls and the ceiling as two surfaces, each rounded up to whole sheets: 18 sheets bare, 19 with the extra. A piece cut from one wall goes on the next, but a ceiling’s offcuts seldom fit a wall.
The drawings show each wall as it would be hung, across in rows with the end joints of one row away from those of the next, or upright if you choose. They show whole sheets, so they are not the count: read the count in the result.
Screws, tape and mud
Three rates turn square feet into the rest of the list, and each has a source.
- Screws. Fine Homebuilding figures about a thousand fasteners for 1,000 sq ft of drywall: one for each square foot. The real count depends on the spacing of the framing.
- Joint compound. USG gives about two pails of 4.5 gal of its ready-mixed compound for 1,000 sq ft: 9 gal. Fine Homebuilding counts 11 gal for a full job of three coats.
- Tape. The calculator adds up the joints of the layout it drew, the corners of each room and the edges of each ceiling: 226 ft for the example. The rule of thumb in the same article is 370 ft for 1,000 sq ft.
Questions about drywall
How many sheets of drywall for a 12×12 room?
With 8 ft walls and a ceiling, and no openings taken out: 528 sq ft, so 19 sheets of 4 × 8 with 10% extra.
How much does a sheet of drywall cover?
32 sq ft for a 4 × 8, 40 for a 4 × 10 and 48 for a 4 × 12.
How much mud do I need per sheet?
At USG’s rate, about 0.29 gal for each 4 × 8 sheet. The 19 sheets of the example take 2 pails of 4.5 gal.
Should drywall be hung across or upright?
That is a choice of the hanger. Across puts one long joint at a height that is easy to tape; upright puts every joint on a stud. The calculator draws either way and counts the same sheets.
Sources
- USG, What is the coverage rate for joint finishing?. About two 4.5 gal pails of Sheetrock UltraLightweight All Purpose Joint Compound finish 1,000 sq ft of gypsum wallboard; the rate is comparable to other USG ready-mixed compounds. Read on .
- Fine Homebuilding, Joint Compound. For rough estimating, around 1,000 fasteners and about 370 linear ft of joint tape for 1,000 sq ft of drywall; a complete three-coat job takes about 11 gal of premixed compound for 1,000 sq ft. Read on .
Updated . How we calculate. Found a mistake? Tell us.