Paint & Walls
Drywall Calculator
Sheets of drywall for walls and ceilings, plus screws, tape and joint compound to finish the job.
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Adjust the inputs to see your result.
About this calculator
Drywall is ordered by the sheet — 4×8 ft is standard, 4×12 ft reduces seams on long walls. This calculator counts sheets from your surface area and adds the finishing materials people forget: screws by the pound, tape by the roll and compound by the bucket.
What this number means
Drywall is a system, not a single product: sheets, screws, tape and compound all scale with the same surface area, and running out of any one of them mid-room costs a store trip with mud drying on the wall. This calculator counts the sheets precisely and the finishing materials by the trade's standard rules of thumb, so the whole list goes on one order.
The rules of thumb are deliberately visible below — a pound of screws per 250 sq ft, about 0.37 ft of tape per sq ft, a gallon of compound per 100 sq ft — so you can sanity-check the list against any supplier's estimate.
The formula
- Surface area = 2 × (Length + Width) × Height, plus Length × Width if the ceiling is included, minus 21 sq ft per door and 15 sq ft per window
- Sheets = Surface × (1 + waste %) ÷ sheet area, rounded up
- Screws ≈ Surface ÷ 250, in pounds
- Joint tape ≈ Surface × 0.37 linear ft, in 250 ft rolls, rounded up
- Joint compound ≈ Surface ÷ 100 gallons, in 4.5 gal buckets, rounded up
Worked example
A 12 × 12 ft room, walls and ceiling, 4×8 sheets.
- Walls = 2 × (12 + 12) × 8 = 384 sq ft; ceiling = 144 sq ft → 528 sq ft of surface
- Sheets before waste = 528 ÷ 32 = 16.5 → 17; with the default 5% allowance: 18 sheets
- Screws ≈ 528 ÷ 250 ≈ 2.1 lb — buy a 5 lb box and you have spares for the next room
- Tape ≈ 528 × 0.37 ≈ 195 ft → 1 roll (250 ft)
- Compound ≈ 528 ÷ 100 ≈ 5.3 gal → 2 buckets (4.5 gal)
Assumptions and limitations
- Finishing quantities assume a standard three-coat tape-and-mud finish at Level 4. Skim-coating whole walls (Level 5) roughly doubles compound use.
- Screw weight assumes #6 coarse-thread screws at typical 12 in field spacing. Glue-and-screw installations use about a third fewer screws and add adhesive tubes not counted here.
- Sheet count is area-based; real layouts waste more when wall lengths fall just over a sheet multiple. If a wall is 12 ft 3 in long, prefer 4×12 sheets stood vertically in your plan even if this count looks similar.
- Corner bead is measured per outside corner (about one 8 ft stick per corner) and is not in this list — count your corners and add it separately.
Frequently asked questions
Walls and ceiling total 528 sq ft with 8 ft ceilings, which is 17 sheets of 4×8 before waste and 18 with a 5% allowance. Walls only would be 384 sq ft — 12 sheets before waste. Enter your room above for your exact layout and sheet size.
4×12 sheets produce far fewer butt joints on long walls and ceilings, and butt joints are the hardest to finish invisibly. But a 4×12 sheet weighs about 50% more and will not turn a stairwell corner. Most DIYers use 4×8 for walls and hire help or a lift if they want 4×12 on ceilings.
Roughly 190 for standard #6 × 1¼ in coarse-thread drywall screws. At the trade rule of 1 lb per 250 sq ft, a 500 sq ft room needs about 2 lb — in practice you buy a 5 lb box because screws are cheap and running out mid-ceiling is not.
About 0.3–0.35 gal per 4×8 sheet for a standard three-coat finish — the calculator works it out from area at roughly 1 gal per 100 sq ft. Pre-mixed compound in 4.5 gal buckets is the convenient buy for room-size jobs; setting-type compound for the first coat is a pro preference, not a requirement.
Only partly — you still hang full or cut sheets over openings and trim the hole out, so the saving is smaller than the opening size. The calculator deducts standard door/window areas because on balance it tracks real orders better, but for a room with one small window the difference is within the waste allowance anyway.