Drywall Calculator
Calculate drywall sheets plus joint compound, screws, and tape - by room size, with door and window deductions and an optional ceiling.
Wall perimeter is calculated automatically from length and width.
Each door deducts 21 ft² from the wall area.
Each window deducts 15 ft² from the wall area.
Your Drywall Estimate
- Enter room length and width - the calculator finds the wall perimeter automatically.
- Enter wall height - 8 ft is standard; 9–10 ft walls suit 4 × 12 sheets to cut down on butt joints.
- Pick the sheet size - bigger sheets mean fewer seams but are heavier to handle.
- Add ceiling and openings (Advanced) - toggle the ceiling and enter doors and windows to deduct.
- Set waste - 10% for a standard room, 15% for small rooms with many cuts.
A 12 by 12 room with 8 foot ceilings needs 14 sheets of 4x8 drywall for the walls - 384 square feet plus 10 percent waste - or 19 sheets if you board the ceiling too. Plan on about 5 gallons of joint compound, 423 screws, and 384 feet of tape for the walls. Enter your room size above; door and window openings are deducted automatically.
How the Sheets Hang
How Much Drywall Do I Need?
Start with the wall area - the room perimeter times the wall height - then subtract the doors and windows, add the ceiling if you are hanging it, add a waste factor, and divide by the coverage of one sheet. A 4 × 8 sheet covers 32 square feet, a 4 × 10 covers 40, and a 4 × 12 covers 48. This calculator does all of that and rounds up to whole sheets.
But sheets are only part of the order. Hanging drywall also needs joint compound, screws, and tape, and the simple "sheets only" calculators leave those out - which is the single most common reason people make a second hardware-store trip. This tool estimates all three alongside the sheet count. It also includes an optional price-per-sheet field for a quick materials cost - and when you want the full installed price including labor, our drywall cost calculator estimates that by finish level and region.
Bigger sheets create fewer seams to tape and finish, so 4 × 12 panels are popular on 9- and 10-foot walls. They are heavier and harder to maneuver, though, so most DIYers stick with 4 × 8.
Drywall Materials Per Sheet
Beyond the panels themselves, a standard three-coat (Level 4) finish needs these supplies - the rule-of-thumb rates this calculator uses:
| Material | Rule of thumb | How it is sold |
|---|---|---|
| Joint compound | ~1 gal per 90 ft² | 1 gal, 3.5 gal, and 4.5 gal buckets |
| Screws | ~1 per ft² (32 per 4×8 sheet) | 1 lb (~320) and 5 lb boxes |
| Joint tape | ~1 linear ft per ft² | 250 ft and 500 ft rolls |
| Corner bead | 1 stick per outside corner | 8 ft and 10 ft lengths |
Sheets by Room Size (8 ft walls, 4×8 sheets, walls only)
| Room (ft) | Wall area | 4×8 Sheets (10% waste) |
|---|---|---|
| 10 × 10 | 320 ft² | 11 |
| 12 × 12 | 384 ft² | 14 |
| 12 × 16 | 448 ft² | 16 |
| 16 × 20 | 576 ft² | 20 |
Before door/window deductions. Add the ceiling (length × width) if you are hanging it.
Drywall Formulas
The room-based method:
Less openings = − 21 ft² per door − 15 ft² per window
Ceiling (opt.) = length × width
Sheets = (net area × (1 + waste)) ÷ sheet coverage, rounded up
Compound / screws / tape = ≈ area ÷ 90 gal · area × 1 screw/ft² · area × 1 ft tape/ft²
Sheet coverage is 32 ft² (4×8), 40 ft² (4×10), or 48 ft² (4×12). Materials are estimates for a standard three-coat finish; textured or Level 5 finishes use more compound.
Code Notes & Sources
- The type of gypsum board and how its fasteners are spaced is governed by IRC Table R702.3.5 - screws land closer at the sheet edges and the seam than in the field, which is why the calculator plans about one fastener per square foot. Ceilings and fire-rated assemblies use tighter spacing.IRC 2021 Table R702.3.5 - Gypsum Board Application and Fastening
- For finishing, the Gypsum Association levels of finish and application standard define how many coats of joint compound each level needs, which is where the roughly one gallon per 90 square feet planning figure comes from.Gypsum Association GA-216 - Application and Finishing of Gypsum Panel Products
Related Calculators
Drywall goes up after framing and before paint - see the full surface calculator collection.
Frequently Asked Questions
How do I calculate how much drywall I will need?
Multiply the room perimeter by the wall height to get the wall area - that is 2 × (length + width) × height. Subtract about 21 square feet per door and 15 per window, add the ceiling (length × width) if you are hanging it, then add 10% for waste and divide by the coverage of one sheet: 32 square feet for a 4×8, 40 for a 4×10, or 48 for a 4×12. Round up to whole sheets. The calculator above does all of this and adds the compound, screws, and tape.
How many sheets of drywall for a 12x12 room?
A 12×12 room with 8-foot walls has about 384 square feet of wall. With 10% waste and 4×8 sheets, that is 14 sheets for the walls. Add the ceiling (144 ft², about 5 more sheets) if you are hanging it, and subtract roughly 21 ft² per door and 15 per window.
How many sheets of drywall for a 1500 sq ft house?
A 1,500-square-foot home has roughly 4,500 square feet of drywall to cover - about three times the floor area, once you count every wall and ceiling. With 4×8 sheets and a 10% waste factor, that is around 140 to 160 sheets, depending on your layout, ceiling heights, and number of interior walls. Calculate each room above and total the sheets, then use our drywall cost calculator to price the installed job.
How many square feet is a 4x8 sheet of drywall?
A 4×8 sheet of drywall covers 32 square feet (4 feet × 8 feet). A 4×10 sheet covers 40 square feet and a 4×12 covers 48. To estimate sheets, take your total drywall area, add about 10% for waste, and divide by the sheet coverage - so a 400-square-foot room needs about 14 sheets of 4×8.
How much joint compound and tape do I need?
Plan on roughly one gallon of all-purpose joint compound per 90 square feet of drywall for a standard three-coat finish, and about one linear foot of tape per square foot. For a typical bedroom that is a few gallons of mud and one 250-foot roll of tape. Buy a little extra - opened compound cannot be returned.
How many screws per sheet of drywall?
About one screw per square foot, which works out to roughly 32 screws for a 4×8 sheet - one every 12 inches in the field and every 8 inches along the edges. A 1 lb box holds around 320 screws, and a 5 lb box covers roughly 30 sheets. Use 1¼-inch screws for ½-inch drywall on wood studs.
Should I use 4x8 or 4x12 sheets?
Use 4×8 sheets for easier handling, especially solo or in small rooms. Use 4×12 sheets on longer or taller walls (9–10 ft) to reduce the number of seams you have to tape and finish, which gives a flatter wall - but they are heavy and usually need two people.
Do I drywall the ceiling or walls first?
Hang the ceiling first, then the walls. The top wall sheets then push up against the ceiling sheets and help support their edges, and the seam ends up easier to finish. Ceilings need more screws and often a panel lift or a helper.
Is there a free drywall calculator app?
You do not need to install an app - this drywall calculator runs free in your browser on any phone, tablet, or computer, with no signup or download. Enter your room size and it returns the sheet count plus the joint compound, screws, and tape you will need. Bookmark it and it is there whenever you need a quick estimate.