Drywall Calculator
Work out how many sheets of drywall a room needs, openings taken out.
Last reviewed September 19, 2026
Result
Enter room length and room width to see the result.
https://calcgallery.com/paint-drywall/drywall-calculator/
Results are estimates for planning only. Actual needs vary with site conditions, products and workmanship. Always confirm quantities with your supplier and follow local building codes and manufacturer instructions. Read the full disclaimer
How to use it
- Enter the room dimensions, or the total area if you have already worked it out.
- Toggle the ceiling on if you are boarding it as well.
- Enter the doors and windows so their areas come out.
- Choose the sheet size you can get, and read the count.
How it is calculated
The walls are the perimeter multiplied by the height, with the ceiling added if you are boarding it and the openings taken out:
Area = 2 × (length + width) × height − doors − windows + ceiling
Sheets = ceil(area × (1 + waste) ÷ sheet area)Sheet area comes from the size you pick, which follows your region: 4 by 8, 4 by 10 and 4 by 12 ft, or 1.2 by 2.4 and 1.2 by 3.0 m.
Screws, tape and joint compound are not estimated. That is a deliberate omission rather than an oversight: the quantities depend on stud spacing, joint treatment and technique, and there is no defensible figure to publish.
Practical tips
Hang sheets horizontally on walls. It puts the long joint at a comfortable working height, gives you fewer linear feet of joint to tape, and ties more studs together. Vertical hanging is for tall walls where a horizontal sheet would not reach.
Ceiling first, then walls. Wall sheets then push up tight against the ceiling boards and support their edges.
Do not butt sheets tightly. A hair of gap at the ends is fine and gets filled. Forcing sheets together bows them and the joint telegraphs through the finish.
Mark the studs on the floor before you lift the sheet. Once a 4 by 12 sheet is against the wall you cannot see where anything is, and screws into fresh air are how you learn that.
Budget more time for taping than hanging. Hanging a room is a day. Finishing it properly is three, spread over as many days as the compound needs to dry. That is the job, not the boarding.
With your numbers
- Area to board = 533 ft²
- Each sheet covers 32 ft²
- With 10% waste, that is 19 sheets
Quick reference
Sheets cut around doors and windows leave offcuts too small to use, so this includes 10% extra.
| Job | Sheets to buy |
|---|---|
| 10 × 12 ft room with ceiling, 4×8 sheets | 15 |
| 12 × 14 ft room with ceiling, 4×8 sheets | 19 |
| 12 × 14 ft room, walls only | 13 |
| 15 × 20 ft room with ceiling, 4×12 sheets | 21 |
| 500 ft² of wall, 4×8 sheets | 18 |
| 4 × 5 m room with ceiling | 23 |
| 5 × 6 m room with ceiling | 30 |
| 60 m² of wall | 23 |
Common questions
- How many sheets of drywall for a 12 by 14 foot room?
- 19 sheets of 4 by 8 ft, boarding the walls and ceiling with one door and two windows, including 10% waste. In 4 by 12 ft sheets it is 13, because bigger sheets mean fewer joints and less offcut.
- Should I use 8, 10 or 12 foot sheets?
- The longest you can carry and fit. Fewer sheets means fewer joints to tape, and taping is most of the work. A 12 ft sheet is unwieldy in a stairwell and worth it in a long hallway.
- Does this include screws, tape and compound?
- No, deliberately. There is no figure for those that survives different stud spacings, joint treatments and how much compound ends up in the bucket, so estimating them here would be inventing a number.
- Why 10% waste?
- Sheets cut around doors, windows and corners leave offcuts too small to use elsewhere. Ten percent is the usual allowance and it is roughly two sheets on a typical room.
- Should I board the ceiling first?
- Yes. Ceiling sheets rest on the top of the wall sheets, which support their edges and hide the joint. Doing the walls first leaves a gap at the top that is awkward to tape.
- Do I subtract every opening?
- Only ones large enough to matter. A door and a window are worth taking out. A light switch is not, and you would cut its hole from a sheet you needed anyway.