Comprehensive Calculator Guide
Wallpaper is counted in strips, not square metres: how many roll-width strips span the wall, and how many wall-height strips one roll yields. A wall 4.2 m wide and 2.7 m high needs 8 strips; a standard 10 m roll gives 3 of them, so you need 3 rolls. Enter the wall and roll sizes to see all three numbers.
Why area alone falls short
Strips run from ceiling to floor, and the offcut left after the last full strip is usually too short for another. The example wall is 11.34 m² and a 0.53 × 10 m roll is 5.3 m², which suggests a little over two rolls. But each roll gives only three 2.7 m strips, leaving 1.9 m unused, and the wall needs eight strips: three rolls.
Strips = wall width ÷ roll width, rounded up. Strips per roll = roll length ÷ wall height, rounded down. Rolls = strips ÷ strips per roll, rounded up.
Roll sizes and pattern repeat
A common roll is about 53 cm by 10 m, with wide rolls around 106 cm; the label gives the exact size. For patterned paper, add the pattern repeat to the wall height: with a 64 cm repeat the example becomes 3.34 m, each roll yields two strips, and you need four rolls. Small doors and windows are usually not subtracted, since strips around them still come from full lengths.
How to Use
- 01Enter the wall's width and height, in metres, centimetres or feet.
- 02Enter the roll width and length from the label.
- 03For patterned paper, add the pattern repeat to the wall height.
- 04Read strips needed, strips per roll and rolls required.
Formula Used
Strips = ⌈ wall width ÷ roll width ⌉ | Per roll = ⌊ roll length ÷ wall height ⌋ | Rolls = ⌈ strips ÷ per roll ⌉Practical Examples
Example 1: standard roll
Wall 4.2 × 2.7 m, roll 0.53 × 10 m: 8 strips, 3 per roll, 3 rolls.
Example 2: wide roll
Wall 3.5 × 2.8 m, roll 1.06 × 15.6 m: 4 strips, 5 per roll, 1 roll.
Example 3: pattern repeat
The first wall with a 64 cm repeat (3.34 m): 8 strips, 2 per roll, 4 rolls.
Important Tips
- Buy one spare roll with the same batch number so colour and print match.
- Measure the height in several places and use the largest.
Common Mistakes to Avoid
- Dividing wall area by roll area, which undercounts rolls.
- Forgetting the pattern repeat on patterned paper.
Frequently Asked Questions
- How many rolls of wallpaper do I need?
- Divide wall width by roll width for strips, roll length by wall height for strips per roll, then divide and round up.
- What size is a wallpaper roll?
- Commonly about 53 cm × 10 m, with wide rolls near 106 cm. Check the label.
- Should I subtract doors and windows?
- Usually not; only very large openings such as a glass wall.
- What is a pattern repeat?
- The distance after which the design repeats. Matching it wastes part of each strip, so add it to the wall height.