Drywall Calculator
Sheets, joint compound, tape, screws and corner bead for walls and ceilings — waste included, with the math shown and the coverage data cited.
Your drywall job
Total length of external corners that need corner bead.
4 × 8 ft sheets (waste included)
19 sheets
- Total drywall area
- 528 ft²
- All-purpose joint compound boxes
- 2 boxes
- Joint tape
- 2 rolls (264 ft)
- Drywall screws
- 586 screws
- Counts round up to whole units — buy a sheet or two extra for damaged, mis-cut or short pieces.
How this is calculated
Gross wall area
perimeter × ceiling height
= 2 × (12 + 12) × 8
384 ft²
Net wall area (openings)
gross wall − Σ openings
= 384 − 0
384 ft²
Total drywall area
net wall + ceiling
= 384 + 144
528 ft²
4 × 8 ft sheet count
ceil((area ÷ sheet area) × (1 + waste% ÷ 100))
= ceil((528 ÷ 32) × (1 + 10 ÷ 100))
19 sheets (17 before waste)
Joint compound
ceil(area ÷ coverage per box)
= ceil(528 ÷ 461)
2 boxes
Tape & screws
area × 0.5 ft/ft² tape · walls × 1 + ceiling × 1.4 screws
= 264 ft tape · 384×1 + 144×1.4
2 rolls, 586 screws
How many sheets of drywall do I need for a 12×12 room?
A 12 ft × 12 ft room with an 8 ft ceiling has a perimeter of 2 × (12 + 12) = 48 ft, so the walls are 48 × 8 = 384 ft². The ceiling adds 12 × 12 = 144 ft², for 528 ft² of board. At 32 ft² per 4×8 sheet that is 16.5 → 17 sheets before waste. Add the standard 10% waste and order 19 sheets. The same math runs for every surface above — the calculator just substitutes your numbers.
Drywall sheets by room size (8 ft ceiling, walls + ceiling, before waste)
| Room size | Total area | 4×8 sheets | 4×12 sheets |
|---|---|---|---|
| 8 × 10 ft | 368 ft² | 12 | 8 |
| 10 × 10 ft | 420 ft² | 14 | 9 |
| 12 × 12 ft | 528 ft² | 17 | 11 |
| 12 × 16 ft | 640 ft² | 20 | 14 |
| 16 × 20 ft | 896 ft² | 28 | 19 |
| 20 × 24 ft | 1,184 ft² | 37 | 25 |
Drywall thickness by application
| Thickness | Typical use |
|---|---|
| 1/4 inch | Curved walls, skim-over a damaged surface |
| 3/8 inch | Repairs, double-layer work |
| 1/2 inch | Standard walls and ceilings (16 in framing) |
| 5/8 inch | Ceilings, fire-rated (Type X) and sound walls |
Finishing materials per square foot of board
| Material | Rate | Per 1,000 ft² |
|---|---|---|
| Joint compound | ~1 box / 461 ft² | ≈ 3 boxes |
| Paper tape | 0.5 ft / ft² | 500 ft (2 × 250 ft rolls) |
| Screws (walls) | 1.0 / ft² | ≈ 1,000 screws |
| Screws (ceiling) | 1.4 / ft² | ≈ 1,400 screws |
Common drywall estimating mistakes
- •Forgetting the ceiling. On most rooms the ceiling adds 25–40% more board on top of the walls — and needs tighter screw spacing.
- •Over-subtracting openings. A standard door or window is worth removing, but small windows leave too little usable offcut to count — this calculator only subtracts openings bigger than ~⅓ of a sheet by default.
- •Skipping waste. Cut-offs, butt joints and damaged corners mean you should order about 10% extra board and a spare box of mud.
- •Under-buying compound. A full three-coat finish uses roughly one 4.5-gallon box per 14 sheets — running short stalls the whole job.
Frequently asked questions
How many sheets of drywall do I need for a 12×12 room?+
A 12×12 ft room with an 8 ft ceiling has 384 ft² of wall plus 144 ft² of ceiling = 528 ft². At 32 ft² per 4×8 sheet that is 17 sheets before waste, or 19 sheets with 10% waste.
How much joint compound and tape do I need?+
Plan on about one 4.5-gallon box of all-purpose compound per 450–475 ft² of board for a full three-coat finish, and roughly 0.5 ft of paper tape per square foot of drywall.
How many drywall screws per sheet?+
About 1.0 screw per ft² on walls and 1.4 per ft² on ceilings — roughly 32 screws per 4×8 wall sheet and 45 per ceiling sheet at 12-inch spacing.
How much waste should I add for drywall?+
Add about 10% for cut-offs, butt joints and damaged pieces. Buy a sheet or two extra on top for rooms with lots of openings or odd angles.
Drywall calculators by job
Sheets
Enter your room size and ceiling height to get the exact number of drywall sheets for the walls and ceiling — waste included, with every formula shown.
OpenMud & Tape
Estimate joint compound, tape and screws for a taping job. Enter the room size to get boxes of mud, rolls of tape and screw counts for a full finish.
OpenCeiling
Calculate drywall just for a ceiling. Enter length and width to get sheets, mud, tape and screws — using the closer fastener spacing ceilings require.
OpenMethodology & sources
Wall area is the room perimeter times the ceiling height; the ceiling adds length × width. Large openings are subtracted, then the net board area is divided by the sheet size, waste is added, and the count is rounded up to whole sheets. Joint compound, tape, screws and corner bead are sized from the same area using published coverage rates.
Coverage varies with finish level, framing spacing and crew technique — always confirm against the product carton and your local building code. Counts round up; buy a little extra for damaged or mis-cut pieces.
- USG Sheetrock Brand Gypsum Panels — standard panel dimensions — verified June 28, 2026
- USG Sheetrock Brand Ready-Mixed Joint Compound — coverage data — verified June 28, 2026
- Gypsum Association GA-216 finishing practice + USG installation guides (taping, fastening and trim rates) — verified June 28, 2026
Last reviewed June 28, 2026. Estimates are indicative — verify against current product specs and local requirements before ordering.
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