Wallpaper Calculator
Planning a wallpaper project requires knowing how many rolls to buy. This calculator uses your room dimensions, wallpaper roll size, and pattern repeat to estimate the number of rolls needed, including a waste allowance for cuts and matching.
The formula calculates the room perimeter, determines how many drops (vertical strips) are needed based on the roll width, and how many drops fit on each roll considering the ceiling height and pattern repeat. A waste percentage accounts for trimming and pattern alignment.
How it works
Rolls = ⌈Total Drops ÷ Drops per Roll⌉ × (1 + Waste%). Total Drops = ⌈Perimeter ÷ Roll Width⌉. Drops per Roll = ⌊Roll Length ÷ Effective Drop Height⌋. Effective Drop Height accounts for pattern repeat alignment.
Use cases
- Estimating wallpaper rolls for a room renovation
- Budgeting material costs for interior decoration
- Comparing different roll sizes and pattern repeats
- Planning purchases to avoid shortages or excess
Frequently asked questions
How many rolls of wallpaper do I need for a room?
It depends on the room perimeter, ceiling height, roll dimensions, and pattern repeat. The calculator divides the perimeter by the roll width to find how many vertical drops you need, then divides the roll length by the effective drop height to see how many drops each roll yields, adding a waste allowance for cuts and matching.
What is a pattern repeat and why does it matter?
The pattern repeat is the vertical distance after which the wallpaper design repeats itself. A larger repeat means you have to waste more paper aligning the pattern across adjacent strips, which increases the number of rolls needed. Plain or random-match papers have little or no repeat and therefore less waste.
How much waste should I add for wallpaper?
A common allowance is around 10% for plain papers and 15% or more for large pattern repeats, to cover trimming at the ceiling and skirting and to match the design. This calculator lets you set the waste percentage so your estimate reflects the specific paper you are using.
Should I subtract doors and windows from the wallpaper estimate?
For most rooms it is safest not to subtract them, because you still need full-height drops beside openings and the offcuts often cannot be reused. Only deduct area for very large openings, and always keep the waste allowance to avoid running short mid-project.
How do I measure a room for wallpaper?
Measure the total perimeter by adding the length of every wall, then measure the ceiling height from floor to ceiling. Enter both along with the roll width and length printed on the wallpaper packaging, and the calculator estimates the number of rolls required.