Drywall Calculator
Work out how much drywall a room needs — wall and ceiling area, sheets with a cutting allowance, and the screws to fix them.
Drywall is bought by the sheet, so the question is always how many sheets — and the answer depends on the room, the ceiling, and the sheet size. This calculator covers all three, plus the screws.
For the joint compound to finish the job, use the drywall mud calculator.
Your results
Enter your measurements and press Calculate.
Quantities are rounded up to whole tiles, planks, boxes or bags, after the wastage allowance. Cost appears only when you enter a price.
Formula
All lengths are converted to a single unit before the calculation: 1 ft = 0.3048 m, 1 in = 25.4 mm, 1 ft² = 0.09290304 m², 1 yd² = 9 ft². Material quantities are rounded up — you cannot buy part of a tile, plank or bag.
How to use this calculator
- Measure the room length, width and height.
- Choose whether the ceiling is included.
- Enter the sheet size (usually 4 × 8 ft).
- Set wastage at 10% and add a price per sheet for a cost estimate.
Worked example
| Room | 12 ft × 15 ft × 8 ft high |
|---|---|
| Wall area | 2 × (12 + 15) × 8 = 432 ft² |
| Ceiling area | 12 × 15 = 180 ft² |
| Total | 432 + 180 = 612 ft² |
| Sheets (4 × 8 ft = 32 ft²) | ⌈(612 × 1.10) ÷ 32⌉ = 22 sheets |
| Screws | 22 × 32 = 704 screws |
Check it by hand: every step above uses the formula in the box. If your numbers match the example inputs but the calculator gives a different answer, please report it via the contact page.
Frequently asked questions
How many drywall sheets do I need?
Divide the total area (walls plus ceiling, if included) by the sheet area, add 10% for cuts and damage, and round up. A 12 × 15 ft room with 8 ft ceilings needs 22 sheets of 4 × 8 ft board — this calculator does the same maths for your room.
What size are drywall sheets?
The standard US sheet is 4 × 8 ft (32 ft²); 4 × 12 ft sheets are common for large rooms and ceilings. In the UK and Australia, 1200 × 2400 mm is standard. Enter your sheet size above.
How many screws per drywall sheet?
About 32 screws per 4 × 8 ft sheet (roughly one every 12 in on studs, closer at edges). This calculator uses 32 per sheet as its estimate — buy a box, not an exact count.
Should I deduct doors and windows?
For drywall, no — sheets are cut around openings and the offcuts are often usable elsewhere. The 10% wastage allowance covers the cutting. If the room has very large openings, the estimate will be slightly generous, which is the safe side.
Related calculators
Estimates only. Results are for planning. Measure twice, confirm box coverage and tile sizes on the packaging you buy, and follow the manufacturer's instructions. See the disclaimer.