Wallpaper Calculator Formula
Understand the math behind the wallpaper calculator. Each variable explained with a worked example.
Formulas Used
Rolls Needed
rolls_needed = ceil(net_area / roll_coverage * 1.10)Net Wall Area
wall_area = net_areaArea with 10% Waste
waste_area = net_area * 1.10Variables
| Variable | Description | Default |
|---|---|---|
room_perimeter | Room Perimeter(ft) | 52 |
wall_height | Wall Height(ft) | 9 |
door_window_sqft | Doors & Windows Area(sq ft) | 40 |
roll_coverage | Roll Coverage(sq ft/roll) | 56 |
gross_wall_area | Derived value= room_perimeter * wall_height | calculated |
net_area | Derived value= gross_wall_area - door_window_sqft | calculated |
How It Works
How to Calculate Wallpaper Rolls
Measure the room perimeter and wall height to get gross wall area. Subtract doors and windows. Add 10% for waste/pattern matching.
Formula
Net Area = (Perimeter x Height) - Doors/Windows
Rolls = ceil(Net Area x 1.10 / Coverage Per Roll)
Worked Example
52 ft perimeter, 9 ft walls, 40 sq ft doors/windows, 56 sq ft rolls.
- 01Gross wall area = 52 x 9 = 468 sq ft
- 02Net area = 468 - 40 = 428 sq ft
- 03With 10% waste = 428 x 1.10 = 470.8 sq ft
- 04Rolls needed = ceil(470.8 / 56) = 9 rolls
Frequently Asked Questions
How much waste should I plan for?
Allow 10% extra for general waste. Patterned wallpaper with large repeats may need 15-20% extra for pattern matching.
How do I measure room perimeter?
Add the lengths of all four walls. For a 14 x 12 ft room: perimeter = 14 + 12 + 14 + 12 = 52 ft.
What is standard wallpaper roll coverage?
US standard single rolls cover about 36 sq ft usable, double rolls about 56-72 sq ft. Check the roll specifications before buying.
Ready to run the numbers?
Open Wallpaper Calculator