Wallpaper Calculator
Estimate how many wallpaper rolls a room needs from room length, room width, wall height, doors, windows, roll size, and waste factor. Use metric or imperial units before entering measurements.
Wallpaper Calculator
Guide
Wallpaper estimate basics
This wallpaper calculator estimates rolls for a simple rectangular room. It uses room length, room width, wall height, door and window deductions, roll size, and waste allowance. For alcoves or separate wall sections, calculate each section and add the results.
Inputs
How to use the wallpaper calculator
Method
How the roll estimate is calculated
- 1
Find the room perimeter from length and width.
- 2
Multiply the perimeter by wall height to estimate gross wall area.
- 3
Subtract door and window openings.
- 4
Calculate roll coverage from roll width and roll length.
- 5
Apply the waste factor and divide by roll coverage.
- 6
Round up, because partial rolls are not usually practical for ordering.
Accuracy
Is the estimate accurate?
The result is an estimate. Pattern repeat, trimming, damaged pieces, angled walls, alcoves, and matching across corners can increase roll use. If the wallpaper has a large repeat or the room has many cuts, use a higher waste factor.
Roll size
Roll width and roll length
Roll coverage is width x length. The calculator uses that full area as the base coverage, then adds waste. Check the product label when possible, because roll sizes vary by region and manufacturer.
Formula
Formula steps
Wall perimeter
2 × (Room length + Room width)
Gross wall area
Wall perimeter × Wall height
Openings area
(Doors × Door area) + (Windows × Window area)
Net wallpaper area
Gross wall area − Openings area
Roll coverage
Roll width × Roll length
Waste-adjusted area
Net wallpaper area × (1 + Waste factor / 100)
Rolls required
Waste-adjusted area ÷ Roll coverage, rounded up
Example
Example calculation
This example uses metric units: a 5 m by 4 m room, 2.5 m wall height, one door, two windows, 0.53 m by 10 m rolls, and 15% waste.
FAQ
Wallpaper calculator FAQ
How many wallpaper rolls do I need for a room?
Enter the room length, room width, wall height, door count, window count, roll size, and waste factor. The calculator estimates the net wallpaper area and divides it by roll coverage.
Why does the calculator ask for room length and width?
Room length and width are used to estimate the wall perimeter. The wall area is calculated as 2 x (length + width) x wall height.
Does this include doors and windows?
Yes. Standard door and window areas are subtracted from the wall area before rolls are estimated.
What roll width and roll length should I enter?
Use the dimensions printed on the wallpaper roll or product listing. Roll coverage is calculated as width x length.
Does this account for pattern repeat?
Not directly. Use a higher waste factor for large pattern repeats, diagonal layouts, or careful matching.
Can deductions exceed wall area?
No. Net wallpaper area is capped at zero, so openings cannot create a negative result.
Sources
- Standard rectangular room wall-area estimate.
- Wallpaper roll coverage is based on roll width x roll length.