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Drywall Calculator
Your room
Example: a 12 ft × 10 ft room with an 8 ft ceiling, one door and one window has 317 sq ft of wall — 10 sheets of 4 × 8 ft drywall, or 11 sheets with 10% waste added.
Behind the numbers
How drywall is measured
Drywall is sold by the sheet, so the job is to turn wall area into sheets. Add up the four walls, subtract a standard door (20 sq ft) and window (15 sq ft), then divide by the sheet area — 32 sq ft for a 4 × 8 ft sheet, 48 sq ft for a 4 × 12 ft sheet — and round up. Screws, compound and tape follow from the same area.
2 × (12 + 10) × 8 = 352 sq ft
352 − (1 × 20 + 1 × 15) = 317 sq ft
317 ÷ 32 = 9.9 → 10 sheets
10 × 28 = 280 screws
317 ÷ 100 = 3.17 → 4 gallons
317 ÷ 350 = 0.91 → 1 roll
A few comparisons
Worked examples
| Room | Result |
|---|---|
| 10 ft × 10 ft room, 8 ft ceiling, 1 door, 1 window | 285 sq ft · 9 sheets (4 × 8 ft) |
| 12 ft × 10 ft room, 8 ft ceiling, 1 door, 1 window | 317 sq ft · 10 sheets (4 × 8 ft) |
| 12 ft × 10 ft room, 8 ft ceiling, 1 door, 1 window, 4 × 12 ft sheets | 317 sq ft · 7 sheets |
| 15 ft × 12 ft room, 9 ft ceiling, 2 doors, 2 windows | 416 sq ft · 13 sheets (4 × 8 ft) |
| 20 ft × 15 ft room, 8 ft ceiling, 2 doors, 3 windows, 4 × 12 ft sheets | 475 sq ft · 10 sheets |
Drywall, without the guesswork.
Add 10% waste for cuts, mistakes and offcuts — check the box above and the sheet count updates.
Use 4 × 12 ft sheets on long walls and 9 ft ceilings: fewer seams means less taping and sanding.
Stagger the vertical seams between rows so no four corners meet at one point.
Count on about 28 screws per 4 × 8 ft sheet and one gallon of joint compound per 100 sq ft of wall.
Good to know
Your drywall questions, answered.
How many drywall sheets do I need for a 12 × 12 room?
A 12 ft × 12 ft room with an 8 ft ceiling has 384 sq ft of wall. Subtract one door and one window (35 sq ft) to get 349 sq ft, which needs 11 sheets of 4 × 8 ft drywall — 12 sheets with 10% waste added.
What size drywall sheet should I use?
4 × 8 ft sheets are the standard choice and the easiest to carry and cut. 4 × 12 ft sheets cover more wall with fewer seams, which helps on long walls and 9 ft ceilings, but they are heavier and need two people to hang.
How many screws do I need per sheet of drywall?
About 28 screws for a 4 × 8 ft sheet and about 36 for a 4 × 12 ft sheet, spaced 12 inches apart on the wall studs. A 10-sheet job needs about 280 screws.
How much joint compound do I need?
About one gallon per 100 sq ft of wall for taping and two finish coats. A 317 sq ft room needs about 4 gallons. If the job is close to a full bucket, buying the 5-gallon bucket is usually cheaper.