About the Wallpaper Calculator
Wallpaper is sold in rolls with a set width and length, and a printed pattern often means some paper is lost matching one strip to the next. This calculator works out how many strips you need to go around the room, how long each strip must be including the pattern repeat and a small trimming allowance, how many strips you can cut from one roll and finally how many rolls to buy. Enter the room's length, width and height, the total area of doors and windows and the details printed on the roll's label.
Updated October 2026
How to use the Wallpaper Calculator
- 1Choose metric or imperial.
- 2Enter the room length, width and wall height.
- 3Enter the total area of doors and windows you won't paper.
- 4Enter the roll width, the roll length and the pattern repeat. Use 0 for plain paper.
- 5Read the number of rolls, with a spare roll suggestion.
How the calculation works
Take a room 4 m by 3.5 m with 2.5 m walls and a 53 cm wide, 10.05 m long roll. The walls total 15 m, minus the 3 square metres of openings divided by the 2.5 m height, so 13.8 m must be covered. That takes 27 strips of 53 cm. Each strip is 2.6 m including trim, so one roll yields 3 strips and the room needs 9 rolls.
A pattern with a 64 cm repeat lengthens each strip to 3.2 m, but three strips still fit on one roll, so the number of rolls stays the same.
Before you hang
- Check every roll for the same batch number.
- Prepare walls: fill holes, sand and apply sizing or lining paper.
- Start from the least visible corner, or from a centred feature.
- Use a plumb line for the first strip, since walls are rarely straight.
- Keep offcuts for patching.
Related tools
Use the Paint Calculator for painted walls, the Flooring Calculator for the floor and the Area Calculator for odd shaped walls. The Unit Converter changes feet and inches into metres and centimetres. The Roofing Calculator helps if you plan outdoor work as well.
Features
- Rolls, strips and strips per roll
- Pattern repeat taken into account
- Allowance for trimming top and bottom
- Deducts doors and windows
- Metric and imperial rolls
- One spare roll suggestion
Frequently asked questions
How do I calculate how many rolls of wallpaper I need?
Find the distance around the room, divide it by the roll width to get the number of strips, work out how many strips of the right length fit in one roll, then divide the strips by that number and round up. The calculator does all of this.
What is a pattern repeat?
It is the distance between one point in the pattern and the next time the same point appears. When strips are hung side by side, the pattern must line up, so each strip is cut to a multiple of the repeat. A larger repeat wastes more paper.
How much extra should I order?
Order at least one spare roll, and make sure all rolls are from the same batch because colours can vary a little. Leftover paper is handy for repairs after a scratch or a leak.
Should I subtract windows and doors?
Only when they are large. The calculator takes the area you give and reduces the wall length by that area divided by the height. A single standard door is about 1.6 square metres, so it saves less than one strip.
Do standard rolls differ between countries?
Yes. UK and European rolls are typically 53 cm wide and 10.05 m long. US single rolls are usually 20.5 inches wide and about 27 feet long, though double and triple rolls are also sold. Check the label of your paper.
Does it work for a feature wall?
Yes. Enter half of the wall's width as the room length and 0 as the room width, which makes the calculator treat the wall's width as the length to cover. Then enter the wall height and read the number of rolls.