Decorating
Wallpaper Calculator
Work out how many wallpaper rolls you need, including pattern repeat waste and an offcut allowance.
Your order
Buy from the same dye lot and add one spare roll for future repairs on patterned papers.
Why wallpaper math trips people up
Wallpaper is sold by the roll but used by the strip, and each strip needs enough length to cover the wall height plus a trim allowance at top and bottom — plus extra if the pattern has to line up (repeat) with the strip next to it. Two rooms of identical square footage can need very different roll counts depending purely on the pattern repeat.
How the repeat eats into coverage
| Pattern repeat | Waste factor | Best for |
|---|---|---|
| None / random match | ~5% | Textures, plains, small all-over prints |
| Small (under 8 in / 20 cm) | ~10-15% | Ditsy florals, geometric small repeats |
| Medium (8-20 in / 20-50 cm) | ~15-25% | Damasks, mid-scale florals |
| Large (20 in+ / 50 cm+) | ~25-35% | Bold statement prints, murals |
Standard roll sizes
| Roll type | Width | Length | Coverage (no waste) |
|---|---|---|---|
| US standard single roll | 20.5 in | 33 ft | ~56 sq ft |
| European roll | 20.5 in (53 cm) | 33 ft (10.05 m) | ~5.3 m² |
| Wide-format / designer roll | 27-36 in | Varies (often 15-24 ft) | Varies — check listing |
Step-by-step hanging order
- Measure total wall width to hang and the ceiling height at the tallest point in the run.
- Divide wall width by roll width to get the number of strips.
- Add the pattern repeat and a trim allowance to the wall height to get strip length.
- Divide roll length by strip length (rounding down) to get strips per roll.
- Divide total strips by strips per roll (rounding up) to get total rolls, calculated per wall.
- Buy an extra roll if the pattern is a special order or discontinued design.
Paste and tools
Paste-the-wall vinyl papers need only a pasted wall and a smoothing brush; paste-the-paper traditional papers need a pasting table, brush, and booking time before hanging. Either way, a standard tub of ready-mixed paste covers roughly five to six rolls — check your specific product's coverage rate since heavier papers use more.
Why do I need extra rolls for a pattern repeat?
Every strip has to line up with the next, so as the repeat gets bigger, more length is trimmed off each strip to keep the pattern aligned. A large 25 in repeat can add 20-30% extra waste compared with a plain or small-repeat paper.
Should I subtract doors and windows from the total?
Only partially. Small and medium openings are usually ignored because the wasted offcuts from full strips can be reused above and below them. Only subtract large openings such as patio doors or picture windows that would otherwise take a full strip out of the run.
Is it better to round up rolls per wall or for the whole room?
Round up per wall. Pattern repeat and strip layout restart at each corner, so leftover partial strips from one wall usually can't be reused cleanly on another, especially with a repeating pattern.
How much paste do I need?
For paste-the-wall products, a standard tub covers roughly 5-6 standard rolls' worth of wall. For paste-the-paper wallpaper, ready-mixed paste typically covers a similar area — check the manufacturer's coverage rate on the tub.
Last reviewed February 2026