How many rolls of wallpaper do you need?

How to use the calculator

Take the measurements with a tape measure: the length and the width of the room along the floor, wall to wall, including niches and projections. Measure the ceiling height at its highest point, otherwise the strip will come up short on a sloped section. Check the roll length on the label: the standard is 10.05 m, but 15 m and 25 m rolls also occur.

Take the roll width from the label as well. The list offers the classic 53 cm, the metre-wide 106 cm and the European 70 cm and 75 cm, and in the rare group the narrow 26 cm and 35 cm for borders and coupon wallpaper, plus the GOST sizes 47 cm and 50 cm per GOST 6810-2002. If your size is missing, choose “Custom size…” and enter the width manually — the calculation is the same.

The number of rolls recalculates on every field change: there is no separate “Calculate” button. Enter the ceiling height and the room dimensions, and the result appears immediately — you can copy it with one button and take it to the shop.

How we calculate

The calculation runs in four steps:

1) Perimeter: (length + width) × 2 — the total wall length to be covered.

2) Strips: divide the perimeter by the roll width and round up. Strips are cut whole, so a fractional remainder ends up as offcuts anyway.

3) Strips from one roll: add 10 cm to the ceiling height for trimming at the top and bottom, and with a pattern repeat add its step as well. Divide the roll length by this height and round down.

4) Rolls: divide the number of strips by the strips from one roll and round up.

The two roundings work in opposite directions: strips round up, strips from a roll round down. That way the calculation never under-buys, even if the room dimensions are uneven.

Why windows and doors are not subtracted

Subtracting the area of a window and a door seems logical, but in practice it leads to a shortage of wallpaper. An opening rarely takes up the full width of a strip: narrow sections remain above and below it that still have to be covered, and the strip has to be cut as a whole. Walls are uneven, corners are not square, and the margin goes into fitting.

Batch is a separate story. Even the same article number from another production run can differ in shade, and a roll bought later will be noticeable in side light. It is easier to take an extra roll straight away than to hunt for the remains of the right batch.

What a pattern repeat is and why it matters

A repeat is the interval at which the pattern repeats. The label gives it in centimetres: 32, 64 and more. Strips are cut so that the pattern continues without a break: each next strip is shifted against the previous one by the length of the repeat. Because of that shift a roll yields fewer strips and there are more offcuts — that is why the calculator adds the repeat to the strip height.

If the pattern does not repeat — plain wallpaper, non-woven for painting, compositions without matching — no repeat is needed: leave “None” and the calculation uses the clean height with a trimming allowance.

We do not subtract windows and doors — offcuts go into pattern matching and corners. Subtract them and the material may run short, while the same shade cannot be bought again.