Drywall Calculator
This drywall calculator works out how many sheets you need, plus the screws, joint compound, and tape. Enter the room size or the total wall and ceiling square footage, pick your sheet size, and add a waste allowance, and you'll get the sheet count rounded up along with the materials list. It's built for a room or a whole house, and it's free and live as you type.
- Sheets needed
- Room or total area
- Any sheet size
- Screws, mud & tape
- Waste allowance
Last updated August 2, 2026 A 4×8 sheet covers 32 sq ft Built by the Calcowa team
Enter the room size or area above 0.
Screws, compound, and tape are planning estimates. Buy a little extra for cuts and mistakes.
528 ft² × 1.10 ÷ 32 = 19 sheets
To work out how much drywall you need, take the wall and ceiling area, add about 10 percent for waste, then divide by the sheet coverage and round up. Drywall, also called sheetrock, comes in panels that cover 32 sq ft (4×8), 40 sq ft (4×10), or 48 sq ft (4×12). A standard 12×12 room comes to roughly 528 sq ft once you add the ceiling, which is about 19 sheets of 4×8, plus near 608 screws, 5 gallons of joint compound, and 211 feet of tape. A standard half-inch 4×8 sheet weighs around 50 to 55 pounds, so line up a second pair of hands for the ceiling.
How many sheets of drywall do I need?
Drywall is sold by the sheet, so the job is area divided by sheet size, with a cushion for cuts. Add the wall area, which is the room's perimeter times the ceiling height, plus the ceiling itself if you're boarding it. Multiply by a waste factor, then divide by the coverage of one sheet, which is 32 square feet for a 4-by-8. A 12-by-12 room with 8-foot walls and a ceiling is about 528 square feet, so with 10 percent waste that's 19 sheets of 4-by-8. The tool runs that and estimates the screws, joint compound, and tape, so you'll leave the store with everything in one trip. It's quicker than sketching it out, and you won't be short a sheet halfway up a wall.
Boarding a 12x12 room, step by step
Here's a 12-by-12 room with 8-foot walls, ceiling included, in 4-by-8 sheets at 10 percent waste. It's the same path the tool runs:
- 1
Find the wall areaPerimeter 2 × (12 + 12) = 48 ft, times 8-foot height, is 384 square feet.
- 2
Add the ceiling12 by 12 is 144 square feet, for 528 square feet total.
- 3
Add the waste528 × 1.10 is about 581 square feet to cover.
- 4
Divide by the sheet581 ÷ 32 is 18.2, which rounds up to 19 sheets.
Sheets by area and size
Here's the sheet count for common surface areas at each sheet size, before waste. The calculator adds your waste and rounds up, so you don't have to, and it's exact for your own room.
| Area | 4 x 8 | 4 x 10 | 4 x 12 |
|---|---|---|---|
| 200 ft² | 7 | 5 | 5 |
| 400 ft² | 13 | 10 | 9 |
| 528 ft² | 17 | 14 | 11 |
| 800 ft² | 25 | 20 | 17 |
| 1,200 ft² | 38 | 30 | 25 |
Frequently asked questions
Find the area you're covering, the walls plus the ceiling if you're doing it, then divide by the area of one sheet and add a little for waste. A 4-by-8 sheet covers 32 square feet, so a room with 528 square feet of surface and 10 percent waste needs about 19 sheets. The tool does the division and rounds up for you, so you'll buy enough without a second trip.
The common sizes are 4 by 8, which is 32 square feet and easy to carry, and 4 by 12, which is 48 square feet and means fewer joints to tape on a big wall. Longer sheets cut down on seams but are heavier and harder to handle solo. Pick the size in the tool and the sheet count updates, so you can compare them.
Ten percent is the usual allowance, since cuts around windows, doors, and outlets create offcuts you can't always reuse. A room with lots of openings or odd angles can run higher, so bump it to 15 percent there. The waste field above defaults to 10, and the sheet count rounds up to whole sheets after the waste is added.
Plan for around 32 screws per 4-by-8 sheet, spacing them about 16 inches apart on the studs and ceiling joists. That works out near one screw per square foot. The tool estimates the total from your sheet count, so for 19 sheets you'd want roughly 600 screws, which is about a 1-pound box and a bit, with some to spare.
A rough guide is about a gallon of joint compound per 100 square feet of drywall across all the coats, and joint tape runs close to half a foot per square foot of board. So a 528-square-foot job takes around 5 gallons of mud and a couple hundred feet of tape. The calculator estimates both, though textured or skim-coat finishes use more.
Yes, they're the same board. Sheetrock is US Gypsum's registered brand name for gypsum panels, and it stuck as an everyday word the way people say Kleenex for tissue. So a sheetrock calculator and a drywall calculator do the same job: you measure the wall and ceiling area the same way, pick the same 4-by-8 or 4-by-12 panels, and the count lands identical. Enter your room above and it works for either name.
Multiply each wall's length by the ceiling height, add the walls together, then add the ceiling as length times width if you're boarding it. A 12-by-12 room with 8-foot walls is 2 × (12 + 12) × 8 = 384 square feet of wall, plus a 144 square-foot ceiling, for 528 square feet. Our square footage calculator handles the area on its own, or the tool above does the area and the sheet count in one step.
Yes to both. There's no sign-up, no limit, and nothing to install, since it runs entirely on your side. The measurements you enter stay on your device and aren't sent anywhere. Bookmark it before a hardware run, and you'll have the sheets, screws, mud, and tape a tap away.
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