Drywall Calculator
This drywall calculator knows drywall is never just sheets — it's sheets plus the joint compound, tape, screws, and corner bead that actually finish the walls, and most calculators only give you the first one. Enter your room's dimensions and get a complete hang-and-finish materials list, with sheet counts compared across all three common panel sizes.
Price edits are remembered on this device — no account, nothing sent anywhere.
regional band ±12%: $246 – $312
Estimates only, not quotes. Prices are editable national averages — confirm current pricing and quantities with your supplier before you buy.
How to calculate how much drywall you need
Start with the area you're covering: the four walls (twice the sum of length and width, times height) plus the ceiling if you're hanging it too, minus real allowances for doors (21 sq ft) and windows (15 sq ft) rather than ignoring them.
That net area gets a waste allowance — 10% by default — before it sizes the sheet count, because waste in drywall is almost entirely cut-offs at the ends of a run and breakage in handling, not the mud or screws. That's why the waste percentage only inflates the sheet count, not the compound, tape, or screw quantities. Four more materials scale off the same net area using standard trade coverage rules: compound by the area one bucket finishes across three coats, tape by linear feet per 1,000 sq ft of board, screws by the area one pound fastens at 16-inch spacing, and corner bead cut into 8-ft sticks.
Everything sold by the piece — sheets, buckets, rolls, pounds, sticks — rounds up to the next whole unit. You can't buy 16.9 sheets of drywall.
The formula
Worked example: drywall sheets for a 12×12 room
The calculator's own defaults: a 12 ft × 12 ft room, 8 ft walls, ceiling included, one door, one window, 4×8 sheets, 10% waste, no outside corners.
- 1. Gross walls2 × (12 + 12) × 8 = 384 sqft
- 2. Plus ceiling+ 144 → 528 sqft
- 3. Minus openings− 21 − 15 → net 492 sqft
- 4. With 10% waste492 × 1.10 = 541.2 sqft
- 5. Sheets4×8: 17 · 4×10: 14 · 4×12: 12
- 6. Compound / tape2 buckets · 1 roll
- 7. Screws / bead2 lb · 0 sticks
- 8. Materials subtotal$221 + $36 + $6 + $16 = $279 ($246–$312 band)
Switching to 4×12 sheets drops the count from 17 to 12 — five fewer full-length joints to tape and mud — at the cost of needing two people to carry each panel.
Assumptions & defaults
| Door / window opening | 21 sqft · 15 sqft each |
| Waste | 10% default — sheets only |
| Compound coverage | 450 sqft per 4.5-gal bucket, three coats |
| Tape usage | ~370 ft per 1,000 sqft · 500-ft rolls |
| Screw coverage | 300 sqft per lb at 16-in spacing |
| Corner bead | 8-ft sticks, outside corners only |
| Prices (editable) | Sheet $13/$16/$19 · bucket $18 · tape $6 · screws $8/lb · bead $4 |
All prices are editable national-average retail estimates, reviewed July 2026.
How many drywall sheets for common room sizes
| Room (8 ft walls) | Wall sqft | 4×8 sheets |
|---|---|---|
| 10 × 10 ft | 320 | 11 |
| 12 × 12 ft | 384 | 14 |
| 12 × 16 ft | 448 | 16 |
| 15 × 20 ft | 560 | 20 |
Walls only, 10% waste, ceiling off, openings not deducted — the calculator above nets all of that out for your real room. The 10% figure is the standard drywall waste factor from the waste factors reference; once the board is hung and finished, the paint calculator knows fresh drywall drinks primer, and the whole approach follows the five-step takeoff method.
Sources & standards
Joint compound, tape, and screw coverage rules follow the finishing-guide figures published by drywall manufacturers and industry references — USG's and National Gypsum's installation and finishing guides, and the Gypsum Association's GA-216 application-and-finishing standard, are the category of document these per-1,000-sq-ft figures are drawn from. Door and window opening allowances follow standard residential estimating figures. Prices reviewed July 2026 — see how our price reviews work.