Drywall calculator

Every line shows the quantity to buy and how StudSheet got it: the spacing, the waste and the package size, so you can check it before the supply house or the quote.

In Canada (4.27 m × 3.66 m room)

Set to Canada, the Sheet works the job out again for Ontario: metric sizes, bag sizes, the frost depth and the code notes. It doesn't just convert feet to meters. The first lines:

• 15 sheets, Drywall 13 mm: Walls, laid out wall by wall: 4 walls (2 × 4.27 m and 2 × 3.66 m), 2 rows across the studs: 8 full + 6 cut for the row ends = 14. Offcuts are reused where they fit; doors and windows are cut out of full sheets. + 1 spare for breakage (about 5%). Covers 33.9 m².
• 6 sheets, Lightweight drywall 13 mm: Ceiling: 3 rows across the joists, 4.27 m long: 3 full + 3 cut for the row ends = 6. Covers 15.6 m².
• ≈693 screws (1.4 kg), Drywall screws, coarse thread: 15 wall sheets × 28 (one every 400 mm on each stud) + 6 ceiling sheets × 35 (one every 300 mm on each joist) + 10% for drops and strips. 13 mm board takes 32 mm screws — at least 15 mm into the wood (NBC 9.29.5.5). About 550 per kg.
• 2 pails, All-purpose joint compound: 49.5 m² of board × 0.41 L per m² for Level 4 (tape + 2 coats) = 20.2 L (USG: about 0.38–0.41 L per m² for a three-coat job).
• 1 roll, Paper joint tape: 60.11 m: about 1.2 m per m² of board (USG), seams and inside corners.
• 2 × 3.78 L, Drywall primer (PVA): 49.5 m² ÷ 27.9 m² per 3.78 L = 6.7 L. Seals the paper and the compound so the paint dries evenly.

1. Before you hang: framing straight and flush (plane or shim high and low studs), blocking at every inside corner and ceiling edge, insulation in, and any framing, wiring, plumbing and insulation inspections signed off.
2. Mark every joist on the top of the walls and every stud on the floor, and measure the outlet boxes and pipes you’ll cut around.
3. Hang drywall on the ceiling first: sheets across the joists, ends staggered and on a joist, screws 12″ apart — a rented drywall lift or a helper holds the sheet.
4. Hang drywall on the walls across the studs: top row tight to the ceiling, bottom row ½″ off the floor; end joints on a stud, staggered row to row and never in line with a door or window edge; screws 16″ apart.
5. Cut out the boxes and the doors and windows you hung over (jab saw or spiral saw), and add a screw wherever an edge isn’t held.
6. Tape coat: fill gaps over ⅛″ with setting-type compound first, then bed paper tape in compound on every seam and inside corner, wipe it tight, and cover the screw heads.
7. Fill coat: a wider coat of premixed compound over the flat seams, the butt joints and the screw heads.
8. Finish coat: a thin coat, feathered wider than the last, on the same seams and screws, plus one coat on the inside corners.
9. Sand: a light pass with a 120–150 grit screen or sponge — never into the paper — then check every joint with a work light held flat to the wall.
10. Prime: one coat of PVA drywall primer before paint.

Must-have tools first, then the ones that help and the ones to rent for the day.

Mistakes that cost a callback or a second trip

• End joints lined up: Butt joints stacked in a line, or on the jamb line of a door or window, crack. Stagger them at least a stud apart and lap sheets over the corners of openings.
• Screws too deep or proud: Torn paper loses its hold; a proud head shows through the compound. A dimpler bit sets them just below the surface.
• Thick coats of premixed compound: They shrink, crack and take days to dry. Thin coats, feathered wide; fill deep gaps with setting-type compound first.
• Drywall touching the floor: It wicks water. Hold the bottom row ½″ up; the baseboard covers the gap.
• Sanding through the paper: Fuzzy paper shows through paint. Sand lightly with 120–150 grit and prime before you judge the finish.

What the calculator assumes

• Sheets counted wall by wall: full rows across the studs (or columns up and down), end joints on framing (a 4×10 on 16″ framing is trimmed to 112″), a ripped strip where the height doesn’t divide (up to 1″ is left at the floor), offcuts reused for row ends where they fit.
• Doors (21 sq ft) and windows (15 sq ft) come out of the area for compound and primer but not out of the sheet count: they’re cut out of full sheets. Big openings (a garage door, an archway, a tub alcove) take whole sheets off.
• Ceiling sheets run across the joists, along the room’s length (joists usually span the short way).
• Screws (IRC Table R702.3.5): walls 16″ apart on 16″ framing, 12″ on 24″ framing; ceilings 12″; at least ⅝″ into the wood (R702.3.6), ⅜″ in from the edges.
• Finish levels (GA-214): Level 2 tape coat only; Level 3 tape + 1 coat; Level 4 tape + 2 coats (inside corners 1); Level 5 adds a skim coat over everything.
• Compound ≈ 10 gal per 1,000 sq ft for Level 4 (USG: 9.4–10), scaled by level; paper tape ≈ 370 ft per 1,000 sq ft (USG).
• Primer: one coat at 300 sq ft/gal.
• Cold weather: keep the space at 55 °F or warmer while you tape and until the compound is dry (USG).

The Sheet sets its code notes for the job's state or province. These are New Jersey's and Ontario's; the code reference has more. Always confirm with your building department.

• Permits: a job like this usually needs none, but towns set their own rules. Ask your building department if you're not sure.

What materials do I need to hang and finish drywall?

For the worked example, a 14′ × 12′ room, the Sheet counts 7 lines with waste included, starting with drywall ½″ (15 sheets), lightweight drywall ½″ (6 sheets), drywall screws, coarse thread (≈693 screws (3 lb)), all-purpose joint compound (2 pails). Each line's math is in the table above. Put in your own sizes in the drywall calculator and every line is counted again.

How long does it take to hang and finish drywall, and can I do it myself?

About 28 to 42 hours for the worked example, in 10 steps. StudSheet stamps it DIY OK: you can do this.

What tools do I need to hang and finish drywall?

28 in all. The must-haves start with tape measure (25 ft), carpenter's pencil, stud finder, chalk line, utility knife + blades, drywall t-square. On the Sheet you mark each one as owned, to buy or to rent.

Stuck while you hang and finish drywall? Ask in the Drywall group of the StudSheet community with this Sheet attached. Homeowners who've done it and verified pros answer, and anyone can read it.

• Drywall for contractors: run this takeoff at your own prices, send the estimate, and get it signed and the deposit paid.
• Patch a hole in drywall (1 patch + 7 small holes): Spackle, patches, compound and primer for nail holes, dents, doorknob holes and bigger cut-outs, and how to make them disappear under paint.
• All 45 Sheets, across 16 trades.
• Code reference: frost depths, guard heights, stairs, retaining walls.