Drywall calculator: how many sheets of drywall do I need?
Measure the room, count the doors and windows, and pick 4x8 or 4x12 sheets. You get sheets with 10% extra for cuts, plus about how much joint compound, tape and screws to buy.
- Walls and ceiling
- 4x8 or 4x12
- Mud, tape and screws
Doors count as 20 sq ft (a 36 x 80 inch door) and windows as 15 sq ft (3 x 5 ft). Compound, tape and screw counts are for hanging and taping new board, not patching. Doing a whole room? The room materials calculator gives paint, flooring, baseboard and drywall from one set of measurements.
Before you hang drywall
How it works
Wall area = 2 × (length + width) × height, minus 20 square feet per door and 15 per window. The ceiling, if you include it, adds length × width.
Sheets = area × (1 + waste) ÷ sheet size, rounded up, for walls and ceiling separately. A 4x8 sheet is 32 square feet and a 4x12 is 48. Waste defaults to 10%, a common allowance for cuts.
Joint compound uses USG's figure of about two 4.5-gallon pails of all-purpose compound per 1,000 square feet of board, or about 9 gallons. Tape uses USG's figure of about 370 feet per 1,000 square feet.
Screws follow the spacing in the International Residential Code for 1/2-inch board on framing 16 inches apart: every 16 inches on walls and every 12 inches on ceilings. That works out to about 28 screws per 4x8 wall sheet and 35 per ceiling sheet.
About this tool
Who it's for
For anyone finishing a basement, a new wall or a room that is getting new board.
Example
You enterA 12x12 room, 8-foot walls, one door, two windows, 4x8 sheets
You get12 sheets, about 3 gallons of compound and 124 feet of tape.
What's different
- Splits wall and ceiling sheets, so you know how many to carry where.
- Adds compound, tape and screws to the list.
- Lets you change the waste allowance.
Gotchas and tips
- Mud amounts vary with the product and how heavy your coats are.
- Taller walls than 8 feet may need a third row of sheets.
- Use moisture-resistant board in bathrooms and other damp rooms.
Privacy: Runs entirely in your browser. Nothing you type is sent to us, and anything it remembers is saved on this device only.
Built and maintained by the GrabTheHammer team, using published figures from manufacturers and agencies, listed below. Updated November 2026. Spot a problem? Tell us.
Drywall questions
How many sheets of drywall do I need for a 12x12 room?
With 8-foot walls, one door and two windows, the walls come to about 330 square feet. With 10% extra that is 12 sheets of 4x8. Add 5 more if you do the ceiling.
Should I use 4x8 or 4x12 sheets?
4x12 sheets mean fewer seams to tape, but they are heavy and hard to get up stairs. 4x8 sheets are easier to carry and fine for most small rooms.
How much joint compound do I need?
USG puts it at about two 4.5-gallon pails of all-purpose compound for every 1,000 square feet of drywall. A typical bedroom needs about one pail.
Sources: USG: joint compound per 1,000 sq ft; USG Sheetrock joint tape coverage; IRC Table R702.3.5 fastener spacing; HomeAdvisor: 10% waste.