Wallpaper Calculator — Rolls Needed with Pattern Repeat

Real-world use cases

• Order one accent wall in a 64 cm repeat floral without over-buying

  You found a floral with a 64 cm straight repeat and want to paper a single 4.0 m wide × 2.7 m high feature wall. Plain "area ÷ roll" math says 10.8 m² ÷ ~5.3 m² per roll ≈ 3 rolls. But the repeat rounds every 270 cm strip up to a 320 cm cut, so a 10.05 m roll yields only 3 strips, you need 8 strips for the width, and that is still 3 rolls — except now you can see exactly why, and that a half-drop version of the same paper would push waste high enough to flirt with a 4th roll. Enter the wall, pick the EU roll preset, set repeat to 64, and read the strip count before you commit.

• Translate a US double-roll bolt into strips for a metric wall

  A paper you love is sold as a US double roll: 27 in wide × 27 ft long. Your wall is in centimetres. Switch the tool to imperial to enter the wall in inches, or stay in metric and use the "US double roll" preset, which loads 68.6 cm × 822.96 cm for you. The shorter 822 cm roll yields fewer strips per roll than a 10.05 m EU roll, so the same wall can need an extra bolt — a difference the "square footage on the box" number hides completely.

• Compare straight vs half-drop before choosing a colourway

  Two colourways of the same damask: one printed as a straight match, one as a half-drop. They cover the same area but not the same number of rolls. Set repeat and roll size once, then flip the match type between straight and half-drop and watch the cut length and waste % change. If the half-drop tips you into one more roll, that is a real cost line for the client estimate — decide with the number, not a guess.

• Estimate a hallway with two doors deducted

  A 6.0 m long hallway, 2.4 m high, with two standard doors totalling 1.8 m of width. Turn on "subtract opening width", enter 180 cm, and the net width drops from 600 to 420 cm — fewer strips, possibly a whole roll less. The tool deliberately keeps the full strip height over the doors because the offcut above a door rarely matches a full strip elsewhere, which is exactly how a pro hangs it.

• Hand a client a defensible material line on a quote

  A decorator quoting a feature wall needs a material count that survives a "why so many rolls?" question. Build the estimate with the real roll spec and repeat, copy the one-line result (rolls, strips needed, cut length, waste %), and paste it into the quote. When the client asks, you point at the repeat-driven waste instead of waving at a square-metre figure that quietly assumed zero pattern matching.

Common pitfalls

• Using "wall area ÷ roll area" for patterned paper. That formula assumes zero pattern matching and zero offcut, so it under-buys almost every patterned wallpaper. Always cut the wall into whole strips and round each strip up to a whole repeat — which is what this tool does.

• Forgetting that a shorter roll yields fewer strips. A US double-roll bolt (about 8.2 m) and an EU roll (10.05 m) can cover the same square metres but yield a different number of full strips, so the shorter roll often needs an extra bolt. Match the roll's real length, not its area.

• Buying rolls from different batches. Wallpaper colour drifts between print runs (dye lots). Ordering all your rolls plus one spare from the same batch at once avoids a visible colour seam that you cannot fix later without re-papering the wall.

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