How to figure how much drywall you need
Drywall is bought by the sheet, so you turn the room into square feet of wall and ceiling, then divide by the size of one sheet. Here is the math with the calculator's starting room: 14 x 12 ft, 8 ft ceiling, one door, two windows and 4 x 8 sheets.
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1
Find the wall area
Perimeter times height: (14 + 12) x 2 = 52 ft, times 8 ft = 416 sq ft.
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2
Take off doors and windows
About 21 sq ft for a door and 15 sq ft for a window. 416 − 21 − 30 = 365 sq ft of wall.
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3
Add 10% and divide by the sheet
A 4 x 8 sheet covers 32 sq ft. Walls: 365 x 1.10 ÷ 32 = 12.5, so 13 sheets. Ceiling: 14 x 12 = 168 sq ft, x 1.10 ÷ 32 = 5.8, so 6 sheets. 19 sheets in all.
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4
Add the finishing materials
533 sq ft of board takes about 4.8 gallons of joint compound (two 4.5 gal pails), about 217 ft of tape with 10% extra (one 500 ft roll), roughly 630 screws and 2 sticks of corner bead. With tools, the total is about $438.
Why count walls and ceiling apart? Ceiling sheets can't share a cut-off with the walls, and many crews use a different board up there. Splitting them gives a more honest count.
Sheet sizes and what they cover
| Sheet | Covers | Best for |
|---|---|---|
| 4 x 8 ft | 32 sq ft | DIY, small rooms, one person, car or small truck |
| 4 x 10 ft | 40 sq ft | Rooms about 10 ft long, 10 ft ceilings hung upright |
| 4 x 12 ft | 48 sq ft | Long walls and ceilings, fewest butt joints, needs two people |
Pick the length that spans a wall with the fewest end-to-end joints. Butt joints, where two short ends meet, are the hardest seams to hide because the ends have no tapered edge.
1/2 inch or 5/8 inch?
Standard 1/2 inch board is right for most walls and ceilings in a house. Use 5/8 inch Type X when you need fire resistance or a stiffer ceiling:
- Garage next to the house. The International Residential Code (section R302.6) asks for at least 1/2 inch board on the garage side of the wall shared with the house, and 5/8 inch Type X on the garage ceiling when there is a living space above.
- Ceilings framed 24 inches on center. 1/2 inch regular board can sag between joists that far apart. Use 5/8 inch or a sag-resistant 1/2 inch ceiling board.
- Quieter rooms. The heavier board blocks a bit more sound between a bedroom and a media room.
For bathrooms, use moisture- and mold-resistant board on the walls. Behind tile in a shower, use cement board or a waterproof backer instead of drywall. Local codes vary, so check with your building department before you hang board in a garage or an addition.
Sheets needed for common rooms
Walls and ceiling, 8 ft ceiling, one door, two windows, 10% extra. Tap a size to load it.
| Room | Board area | 4 x 8 | 4 x 12 |
|---|---|---|---|
| 10 x 10 | 369 sq ft | 14 | 10 |
| 10 x 12 | 421 sq ft | 16 | 10 |
| 12 x 12 | 477 sq ft | 17 | 12 |
| 12 x 14 | 533 sq ft | 19 | 13 |
| 14 x 16 | 653 sq ft | 23 | 16 |
| 16 x 20 | 845 sq ft | 30 | 21 |
| 24 x 24 garage | 1,293 sq ft | 45 | 31 |
Mud, tape and screws per 1,000 sq ft
| Material | Per 1,000 sq ft of board |
|---|---|
| Lightweight all-purpose joint compound | About 9 gal (two 4.5 gal pails) |
| Paper joint tape | About 370 ft |
| Screws, walls at 16" spacing | About 875 |
| Screws, ceilings at 12" spacing | About 1,100 |
These rates assume three coats over the tape and a smooth, paint-ready finish (what the trade calls Level 4). Heavier compound covers less per pail by volume, and a skim coat over the whole wall (Level 5) can double the mud.
What it costs
Board is the biggest line on a DIY list. A 1/2 inch 4 x 8 sheet runs about $15 to $17 at big-box stores, and 5/8 inch Type X a few dollars more. For a pro, hanging and finishing usually runs $1.50 to $3.50 per square foot with materials. Ceilings, tall walls, stairwells and a Level 5 finish land at the top of that range. Taping is the skilled part: many DIYers hang their own board and hire a finisher for the mud.
Tips from the trade
- Ceiling first, then walls. The wall sheets hold up the edges of the ceiling board.
- Top row first on walls. Press the upper sheet tight to the ceiling and leave any gap at the floor, where the baseboard hides it.
- Don't line seams up with door and window corners. Cut the sheet around the opening in an L shape. Seams that start at a corner crack.
- Stagger the butt joints so they don't land on the same stud row after row.
- Set screws just below the surface. Dimple the paper without tearing it. A dimpler bit makes this easy.
- Rent a drywall lift for ceilings. It costs far less than a sore neck and a cracked sheet.
Common questions
How many sheets of drywall do I need for a 12x12 room?
A 12x12 room with 8-foot ceilings, one door and two windows has about 333 square feet of wall and 144 square feet of ceiling. With 10% extra, that is 12 sheets of 4x8 for the walls and 5 for the ceiling, 17 in all.
Should drywall be hung horizontally or vertically?
On walls 8 or 9 feet tall, most pros hang it horizontally. It leaves fewer feet of seam, puts the long seam at a comfortable working height and bridges uneven studs better. Vertical hanging is common in commercial work and on tall walls.
Should I use 1/2 or 5/8 inch drywall?
Use 1/2 inch for most walls and ceilings in a house. Use 5/8 inch Type X where the building code calls for fire resistance, such as a garage ceiling with a room above it, and on ceilings with framing 24 inches on center to prevent sagging.
How much does it cost to drywall a room?
Hanging and finishing drywall usually costs $1.50 to $3.50 per square foot of board with materials. A 12x14 room with an 8-foot ceiling has about 530 square feet, so expect roughly $800 to $1,870 for a pro or about $440 in materials doing it yourself.
How much joint compound do I need per sheet of drywall?
USG estimates about two 4.5 gallon pails of lightweight all-purpose compound to finish 1,000 square feet of board. That works out to roughly a quarter gallon per 4x8 sheet for three coats over the tape and screws.
How many screws per sheet of drywall?
A 4x8 sheet on walls with studs 16 inches on center takes about 28 to 32 screws at 16 inch spacing. Ceilings need closer spacing, about 12 inches, so plan on 35 to 40 screws per sheet.
Sources and assumptions
Prices are US averages checked in October 2026 and vary by region and store. The sheet price can be edited in the calculator.
- Joint compound: USG FAQ, compound needed per 1,000 sq ft. Georgia-Pacific's Wallworks guide gives a lower figure (one 61.7 lb pail per 800 sq ft); we use USG's to avoid running short.
- Tape: about 370 ft per 1,000 sq ft, as printed on USG Sheetrock joint tape; plus 10%.
- Screws: about 875 per 1,000 sq ft at 16 inch spacing and 1,100 at 12 inch, from the USG fastener table reproduced by InspectApedia; plus 10% for drops. Boxed as 1 lb, about 250 screws.
- Sheet prices: Home Depot drywall sheets (1/2 inch 4 x 8 about $15.58). Defaults: 1/2 inch $16, $20, $24 and 5/8 inch $18, $23, $27 for 4 x 8, 4 x 10 and 4 x 12.
- Pro cost: HomeAdvisor, drywall installation cost, $1.50 to $3.50 per sq ft including materials.
- Garage separation: International Residential Code, section R302.6.
- Openings: 21 sq ft per door (about 3 x 7 ft) and 15 sq ft per window. Other supplies at typical shelf prices: 4.5 gal compound $24, 500 ft tape $8, 1 lb screws $9, 8 ft corner bead $4.50 (10 ft $5.50), knives and pan $30, sanding sponges and screen $12.