These answers explain the assumptions behind the RoomRoll Calculator. Your wallpaper manufacturer or installer may give different instructions for a particular product, so always check product-specific guidance before buying.
How many square metres does one wallpaper roll cover?
Multiply the roll width by its length to calculate nominal area. For example, a roll 0.53 metres wide and 10 metres long has a nominal area of 5.3 square metres. Usable coverage can be lower because of trimming, pattern repeat, wall height and installation technique. The number on the package or supplier listing should be checked before ordering.
How do I measure a room for wallpaper?
For a simple rectangular room, measure the length and width and add them together, then multiply by two to get the perimeter. Multiply the perimeter by wall height to estimate wall area. Measure unusual walls, sloped ceilings and alcoves separately. A professional installer can create a more precise strip layout when the room is irregular.
Why does the calculator ask for roll width and length?
Roll dimensions determine both nominal coverage and how many full-height strips might fit on a roll. Different products have different dimensions, so a generic roll assumption can produce a misleading estimate. Use the exact measurements from the product label, and confirm whether the product is sold as one roll or a package.
How much extra wallpaper should I buy?
The correct allowance depends on the wallpaper design, pattern repeat, wall shape, cutting method and installer. This tool provides 10%, 15% and 20% as planning scenarios, not guarantees. Follow manufacturer advice and ask for a product-specific estimate when the design has a large repeat or the room has complex features.
Should I subtract windows and doors?
Not automatically. Wallpaper strips still need to be cut around openings, and offcuts may not be reusable because of their size or pattern position. The optional door setting subtracts a rough fixed area for one or two standard doors only; it is not an exact measurement. For a conservative estimate, leave openings included until the layout is planned.
Does the tool account for pattern repeat?
The calculator adds a waste allowance and performs a simplified strip-based check, but it does not calculate exact pattern matching or offset repeats. Large patterns can increase material needs. Check the pattern repeat on the product label and ask the supplier or installer to confirm the number of rolls.
How is the roll count rounded?
The estimate rounds up to a whole roll because partial rolls are not always sold and a small shortfall can interrupt a project. It compares an area-based estimate with a simplified strip-based estimate and uses the higher result. The calculation still cannot guarantee the exact quantity for every room.
How is the material cost calculated?
Enter the price per roll and choose a currency symbol. The calculator multiplies the entered price by the estimated number of rolls. It does not retrieve live prices and does not include labour, paste, preparation, delivery, taxes or other supplies. Check the unit that the seller uses for its price.
Can I use feet and inches?
Room length, width and wall height accept metres or feet. Roll width accepts metres, centimetres or inches, and roll length accepts metres or feet. The tool converts the values into metres before calculating. Check that the selected unit matches the number entered, especially when switching between centimetres and metres.
Can I use this for wallpaper murals?
Use caution. Murals often have numbered panels, specific alignment requirements and product-specific instructions. A standard roll-area calculation may not reflect the mural layout. Follow the mural manufacturer’s panel instructions and confirm the number of sets or panels required for your wall.
Does the calculator work for sloped ceilings or staircases?
The simple rectangular-room method is not designed for complex wall geometry, staircases or sloping ceilings. You can calculate individual sections separately for a rough planning estimate, but do not combine estimates blindly if patterns must line up across sections. A professional measurement is recommended for these layouts.
Does the cost estimate include installation?
No. It estimates wallpaper material only. Installation labour, wall preparation, primer, paste, tools, delivery, taxes and disposal costs are excluded unless you include them separately in your own budget.
Is this calculator a guarantee of the right number of rolls?
No. It is an informational planning tool based on entered measurements and assumptions. Product dimensions, pattern matching, room shape and installation choices can change the result. Verify the quantity with the manufacturer, supplier or installer before purchasing.
Still have a question?
Review the calculation method and the wallpaper planning guide. If you want to send feedback about the tool, visit the Contact page.
Can I calculate wallpaper for only one feature wall?
Yes, but use the feature wall's actual width and height rather than the full room perimeter. The current calculator is designed around a rectangular room and uses the room length and width to estimate the perimeter. For a single wall, a rough manual approach is to estimate that wall's area, add an appropriate allowance, and compare it with the nominal roll area. This manual method still does not account for strip layout or pattern matching, so confirm the quantity with the supplier.
What if my walls have different heights?
A single wall-height field assumes a relatively regular room. If the heights vary, measure the wall sections separately and seek a wall-by-wall calculation. Using an average height can underestimate material at the tallest point, while using the tallest height everywhere can overestimate it. Sloped ceilings and staircases need particular care because the shape and direction of the strips can change the cutting plan.
Why might an installer recommend more rolls than the calculator?
An installer may account for pattern repeat, matching across corners, the direction of the design, wall defects, unusable offcuts, difficult access or a product-specific installation method. They may also use exact strip counts rather than area alone. The tool intentionally provides an estimate from a limited set of measurements, so a higher professional estimate is not automatically incorrect.
Should I keep leftover wallpaper?
Keeping a labelled leftover piece or an unopened roll can be useful for later repairs, especially if the design or batch becomes unavailable. Store it according to the manufacturer's instructions and retain the product label, pattern number and batch details. Check the seller's return terms before opening packages, because return rules vary by retailer and product.
What should I do if the result seems too low?
Check that the room measurements and units are correct, verify roll width and length, and make sure the selected waste allowance reflects the product. Consider whether the room has extra walls, alcoves or pattern repeats that the calculator does not model. If the result still seems low, leave openings included and ask the supplier or installer for a detailed calculation before purchasing.