What is a Drywall Calculator?
A Drywall Calculator helps you determine exactly how many drywall sheets (also known as plasterboard or gypsum board) you need for a construction or renovation project. Instead of manually measuring walls, calculating areas, and guessing how many sheets to buy, this tool handles all the math for you.
Why Accurate Estimation Matters
Ordering too few sheets means project delays and extra trips to the store. Ordering too many wastes money and materials. A proper drywall estimate accounts for:
Room Geometry
Openings
Waste Factor
Sheet Orientation
How to Use the Drywall Calculator
Select Your Unit System
Choose Metric (meters) or Imperial (feet) using the toggle at the top of the calculator.
Enter Room Dimensions
In Quick mode, enter length, width, and height. For non-rectangular rooms, switch to Custom mode and add individual wall measurements.
Toggle Ceiling
Check "Include Ceiling" if you also need to drywall the ceiling area.
Add Openings
Use the preset door and window sizes, or enter custom opening dimensions. Increase the quantity for each type to match your room.
Configure Sheet Settings
Select your preferred sheet size (1200×2400, 1200×2700, or 1200×3000 mm), orientation, thickness, board type, and waste factor.
View Results
The calculator instantly shows total sheets needed, area breakdown, and per-section sheet counts.
Multi-Room Projects
Click Add Room to calculate multiple rooms in one session. Each room maintains its own dimensions, openings, and ceiling settings. Use the tab bar to switch between rooms. You can rename, duplicate, or delete rooms from the menu.
Accessories and Cost
Expand the Accessories Estimate section to see estimated quantities for screws, joint tape, joint compound, corner bead, and metal studs. Expand Cost Estimate to enter prices and get a total material cost. You can select your local currency from the dropdown.
Features
Quick and Custom Input Modes
Quick mode lets you enter a simple length, width, and height for rectangular rooms. Custom mode allows you to define each wall individually — useful for L-shaped rooms, rooms with varying wall heights, or partial walls.
Openings Deduction
Choose from preset door and window sizes or enter custom dimensions. The calculator automatically subtracts opening areas from the total wall area before computing sheet counts.
Sheet Configuration
Select from three standard sheet sizes, three thickness options, and three board types. Choose horizontal or vertical orientation based on your installation needs.
- Sizes: 1200×2400, 1200×2700, 1200×3000 mm
- Thickness: 9.5, 12.5, 15 mm
- Types: Standard, Moisture-resistant, Fire-resistant
Adjustable Waste Factor
Pick a preset waste percentage (10%, 15%, 20%) or enter a custom value. The waste factor accounts for cuts, fitting around corners, and damaged sheets during installation.
Multi-Room Support
Add unlimited rooms with individual settings. Rename, duplicate, or delete rooms from the tab menu. A summary card shows the per-room and total sheet counts across all rooms.
Accessories Estimate
Get estimated quantities for drywall screws, joint tape, joint compound, corner bead, and metal studs. Stud spacing is adjustable between 400 mm and 600 mm centers.
Cost Estimator
Enter the price per sheet and price per screw box to get an instant cost breakdown. Select your currency from the built-in picker for proper formatting.
PDF Export
Generate a complete PDF report with sheet configuration, room-by-room calculations, accessories, and cost estimates. The report uses your selected currency for all monetary values.
Data Persistence
Your input data, room configurations, and settings are automatically saved and restored when you revisit the calculator.
Frequently Asked Questions
How is the number of drywall sheets calculated?
The calculator computes the total wall area (perimeter × height), adds ceiling area if included, subtracts door and window openings, applies the waste factor, and divides by the sheet area. The result is rounded up to the nearest whole sheet.
Calculate Area
Wall + ceiling area
Subtract Openings
Doors & windows
Apply Waste
Add waste factor
Divide & Round
Get sheet count
What waste factor should I use?
10% Waste
15% Waste Default
20%+ Waste
What is the difference between horizontal and vertical orientation?
Industry Standard Recommended
- Sheets placed sideways
- Creates fewer joints
- Easier to tape and finish
- Standard waste factor
Special Cases
- Sheets placed upright
- More joints to finish
- Used for shorter walls
- +5% additional waste
How are accessories calculated?
| Accessory | Calculation Method | Rate |
|---|---|---|
| Screws | Per sheet, scaled by size | ~32 per standard sheet |
| Joint Tape | Per square meter of net area | 1.5 m per m² |
| Joint Compound | Per square meter of net area | 0.5 kg per m² |
| Corner Bead | 4 corners × room height | 4 corners standard |
| Metal Studs | Wall width ÷ stud spacing | 400–600 mm centers |
Can I calculate multiple rooms at once?
Yes. Click Add Room to create additional rooms. Each room has its own dimensions, mode, openings, and ceiling setting. The sheet configuration (size, waste, orientation) is shared across all rooms. A summary card shows the total for all rooms combined.
- Add unlimited rooms to your project
- Individual dimensions and openings per room
- Rename, duplicate, or delete rooms easily
- Shared sheet configuration across all rooms
- Automatic summary with grand totals
Is my data saved?
Yes. All your input data, room configurations, and settings are automatically saved to your browser's local storage. When you return to the calculator, everything is restored exactly as you left it.
No comments yet. Be the first to comment!