Free calculator
Drywall calculator
Enter your room size to see how many drywall sheets you need in each standard length, with the walls and the ceiling counted separately. Subtract openings if you like and adjust the waste allowance.
Drywall calculator
Calculated on lokalmatch.com
Your results
| Sheet size | Walls | Ceiling | Total |
|---|---|---|---|
| 4 × 8 ft1,220 × 2,440 mm | 13 | 5 | 18 |
| 4 × 10 ft1,220 × 3,050 mm | 10 | 4 | 14 |
| 4 × 12 ft1,220 × 3,660 mm | 9 | 3 | 12 |
- Wall area (net)
- 352sq ft
- Ceiling area
- 120sq ft
Ceilings often take a different board, so walls and ceiling are counted separately.
Estimates for planning only. Confirm quantities with your supplier or contractor before you order.
On this page
How to measure for the drywall calculator
- Measure the length and width of the room at floor level, and the wall height from floor to ceiling.
- For an irregular room, calculate each rectangular section separately and add the sheets together.
- If you want to subtract doors and windows, measure them and enter their total area.
- Pick the sheet length that suits your walls: longer sheets mean fewer joints but are heavier to carry and lift.
Assumptions behind the drywall calculator
Every default below appears in the calculator and can be changed.
- Wall area = 2 × (length + width) × height. Ceiling area = length × width.
- Sheets are 4 ft (1220 mm) wide and 8, 10 or 12 ft (2440, 3050 or 3660 mm) long, as listed on CGC’s product data sheet.
- Default waste: 10% for offcuts and damaged sheets. It’s our starting point, not a standard.
- Openings default to 0, which keeps the estimate on the cautious side. Enter their area to subtract them.
- Walls and ceiling are rounded up to whole sheets separately. Joint compound, tape, corner bead and screws are not included.
| Sheet | Metric size | Coverage |
|---|---|---|
| 4 × 8 ft | 1,220 × 2,440 mm | 32 sq ft (2.97 m²) |
| 4 × 10 ft | 1,220 × 3,050 mm | 40 sq ft (3.72 m²) |
| 4 × 12 ft | 1,220 × 3,660 mm | 48 sq ft (4.46 m²) |
Drywall calculator: tips before you buy
- Check which board your project needs: moisture-resistant or fire-rated panels may be required in some rooms. Your municipality’s building department can confirm.
- Sketch the layout on paper first to limit joints, especially on the ceiling.
- Plan how the sheets will get inside: a 12 ft sheet may not fit up a narrow staircase.
- Keep a few offcuts for patches once the other trades are done.
Drywall calculator: frequently asked questions
How many sheets of drywall do I need for a 12 × 12 room?
With 8 ft walls, the four walls are 384 sq ft and the ceiling is 144 sq ft. Without waste, that’s 12 sheets of 4 × 8 for the walls and 5 for the ceiling; with the default 10% waste, 14 and 5. Enter your own sizes to check.
Which sheet size should I choose?
Longer sheets cover more wall with fewer joints to tape, but they are heavier and harder to bring inside. The calculator shows 4 × 8, 4 × 10 and 4 × 12 side by side so you can compare.
Should I subtract doors and windows?
You can. Leaving them in adds a margin for mistakes; enter the total area of the openings to subtract them.
Sources for the drywall calculator
We checked these references on September 10, 2026. Product figures vary, so read the label or data sheet of the product you choose.
Last reviewed September 10, 2026
Pros for this project
Other calculators
Prefer to have a pro measure?
Describe your project and get free quotes from local pros who can confirm quantities on site.