Measure the width of each wall at its widest point using a tape measure. For the height, measure from the floor to the ceiling at multiple points and use the tallest measurement. Always measure in meters (or feet) to two decimal places. Don't forget to account for alcoves, recesses, and any irregular features. It's better to over-measure slightly than to run short.

Pattern repeat is the vertical distance between one instance of the pattern and the next identical instance. When hanging wallpaper with a pattern, each strip must be aligned so the pattern matches horizontally. This means extra length is needed per strip — sometimes up to the full repeat distance. As a rule of thumb, a pattern repeat of 32cm or more can increase waste by 10-20%. Always check the label on your wallpaper roll for the exact repeat measurement.

Yes, you can subtract the area of doors, windows, and other large openings from your total wall area. However, many professionals recommend only subtracting very large openings (like patio doors or bay windows) and leaving smaller windows and standard doors in the calculation as a safety buffer. The wallpaper around these openings often results in offcuts that cannot be reused elsewhere.

We recommend purchasing at least 1 extra roll beyond the calculated amount, especially if your wallpaper has a large pattern repeat or if you're a first-time installer. Wallpaper dye lots can vary between production batches, so buying extra upfront ensures color consistency. If you have a complex room with many corners, add 2 extra rolls. Leftover rolls can also be useful for future repairs.

European standard: 10.05m long × 0.53m wide (covers approx. 5.3m² per roll).
Wide European: 10.05m long × 1.06m wide (covers approx. 10.6m² per roll).
US standard: 33ft long × 21in wide (covers approx. 57.75 sq ft per roll).
Always verify the dimensions on the label before purchasing, as some manufacturers use different sizes.

If your ceiling height exceeds the roll length, you cannot hang the wallpaper vertically in a single piece. In this case, you may need to install the wallpaper horizontally (rotated 90°), which changes the calculation entirely. Alternatively, you can create a horizontal join with a chair rail or dado rail to split the wall. For very tall walls, consider using extra-long rolls or commercial-grade wallcoverings.

The waste factor accounts for several real-world losses: trimming at the top and bottom of each strip (typically 5-10cm per strip), pattern matching offcuts, mistakes during cutting or hanging, and unusable portions at the end of each roll. A 10% waste factor is standard for plain wallpapers, while 15-20% is recommended for patterns with large repeats. This ensures you won't run short mid-project.

Yes! This calculator works perfectly for peel-and-stick (self-adhesive) wallpaper as well. The same principles apply — you need to know the roll dimensions and your wall measurements. Peel-and-stick wallpaper often comes in slightly different roll sizes (commonly 3m or 5m lengths), so be sure to enter the correct roll length and width from your product's packaging.