How to use this calculator
Measure one wall and copy the roll dimensions and pattern repeat from the product label. Include the combined top and bottom trimming allowance. Enter zero for the pattern repeat if there is no pattern to align.
The formula
A worked example
For a 4 × 2.4 m wall, a 0.53 × 10.05 m roll, 0.10 m trim and 0.64 m repeat: 8 strips are required. Each is 2.56 m long; a roll yields 3 strips, so buy 3 rolls.
Assumptions & limitations
For one rectangular wall and a straight-match pattern only. Offset, half-drop, A/B rolls, and multiple walls may need a different cutting plan. Openings are not subtracted because full strips may still be needed. Aligning the starting pattern on a new roll may require extra trim beyond this simplified model.
Common questions
Why does the pattern repeat change the result?
Each strip is rounded up to a complete repeat so identical pattern positions can align. This uses extra paper.
Can I use this for half-drop wallpaper?
No. Offset matching can require alternating cuts and more waste. Ask the supplier for the specific layout.
Supporting reference
The method above states this calculator’s assumptions. This reference provides related definitions and technical context.
Graham & Brown: measuring your room ↗Formula and worked example checked against automated test cases. About our methodology.