How rolls are counted
Strips needed = ⌈total wall width ÷ roll width⌉
Strip length = wall height + pattern repeat + trim allowance
Strips per roll = ⌊roll length ÷ strip length⌋
Rolls = ⌈strips needed ÷ strips per roll⌉
Counting strips instead of dividing areas accounts for the offcut at the end of every roll, which is where most estimates go wrong. Doors and windows are not deducted: strips around them are usually cut from full lengths. Roll sizes vary by manufacturer, so use the width and length on the label, along with the pattern repeat.
Worked example
48 ft of wall, 8 ft high, 20.5 in × 33 ft rolls, 21 in pattern repeat, 4 in trim allowance:
| Strips needed (576 in ÷ 20.5 in) | 29 |
|---|---|
| Strip length (96 + 21 + 4 in) | 10.08 ft |
| Strips per roll | 3 |
| Rolls | 10 |
Buy all rolls from the same batch (dye lot), and one extra for mistakes and future repairs.
Frequently asked questions
Do I subtract doors and windows?
Generally no for small openings, because the strips around them are cut from full-length pieces. Over a very large window or wide opening you can deduct part of a strip.
What is a pattern repeat?
The vertical distance before the design repeats. Matching it means each strip must start at the same point in the pattern, which wastes paper.