Loona Construction Calculators
How many rolls of wallpaper does a room take? Enter the room, choose a European roll (0.53 × 10.05 m) or a US double roll, and add your pattern repeat — the calculator works in strips, exactly like a decorator, so repeats and trimming are properly allowed for.
Count in strips: divide the roll length by your strip length (wall height + trimming, rounded up to the pattern repeat) to get strips per roll, then divide the wall area by the usable area of one roll. A typical 4 × 3.5 m room takes about 10–11 European rolls.
The repeat is the distance before the pattern matches again (printed on the label, e.g. 53 cm). Every strip must start at a matching point, so each strip is rounded up to a whole number of repeats — the offcut is waste. Large repeats on tall walls can add a roll or two.
The European standard roll is 0.53 m wide × 10.05 m long (about 5.3 m²). US papers are sold as single or double rolls; a double roll is typically 27 in × 27 ft. This calculator offers the European roll and the US double roll.
Decorators count wallpaper in strips, not square metres:
Strip length = Wall height + 10 cm trimming, rounded up to a whole number of pattern repeats
Strips per roll = Roll length ÷ Strip length (whole strips only)
Usable area per roll = Roll width × Strips per roll × Wall height
Rolls = Net wall area × (1 + Waste %) ÷ Usable area per roll, rounded up
Net wall area subtracts standard doors (1.89 m²) and windows (1.8 m²) from the full wall area.
Yes for wallpaper — unlike plasterboard, offcuts above doors are short and genuinely reduce what you hang, so standard doors (1.89 m²) and windows (1.8 m²) are deducted from the wall area here.
The 10% allowance covers mis-cuts and the strip that starts a new wall. Beyond that, always buy every roll in one order from the same batch — dye lots differ visibly, and a later top-up roll may not match.
Yes — switch to Imperial for feet and inches (pattern repeat in inches). Roll definitions stay the physical European and US standards, so counts are directly comparable.
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