Do I subtract doors and windows?

You can leave small ones in as a safety margin; only subtract large openings, and even then keep a little extra for mistakes.

What is pattern repeat?

It's the vertical distance before the design repeats; a bigger repeat means more paper wasted when matching adjacent strips.

Why does batch number matter?

Colour can vary slightly between print runs, so rolls from different batches may show as faint bands on the wall.

How Much Wallpaper Do You Need?

Published 10/6/2025 · 3 min read · Everyday calculators

Marco Bianchi — Home, DIY & motoring writer at Allin

Renovation · Materials

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In short

Measure the wall area (perimeter × height), divide by the usable area of one roll, then add for pattern repeat and trimming. A standard roll covers about 5 m² after waste. A room with 30 m² of wall needs 30 ÷ 5 = 6 rolls; add a roll for a large pattern repeat, and always buy from the same batch.

A woman hanging patterned wallpaper, paste tins at her feet. — Nataliya Vaitkevich · Pexels · Pexels

Measure the wall area, divide by a roll's usable coverage, then add for pattern repeat. Here's the method, with an example and why batch numbers matter.

Measure the walls

Add the width of every wall to get the perimeter, then multiply by the ceiling height. A 4 × 3 m room has a 14 m perimeter, and at 2.5 m high that is 35 m² of wall. You can leave small doors and windows in the total — the extra acts as a safety margin against mistakes and matching.

Coverage per roll

A standard roll is about 10 m long and 0.53 m wide — around 5.3 m² of paper. But you rarely use all of it: trimming top and bottom, and matching the pattern between strips, eats into the total, leaving closer to 5 m² of usable coverage, sometimes less. Use the usable figure, not the raw roll size, when you divide.

Pattern repeat and waste

The pattern repeat is the vertical distance before the design starts again. A plain or small-repeat paper wastes little; a large repeat forces you to slide each strip up or down to line the pattern up, throwing away offcuts every drop. For big or offset (drop-match) repeats, add 10–15% or a whole extra roll to be safe.

Buy the same batch, keep offcuts

Every roll carries a batch (shade) number, and colour can drift slightly between print runs — mismatched batches show as faint bands on the finished wall. Buy all your rolls with the same number in one go, and keep an unopened roll or large offcut afterwards, so a scuff or a future repair can be patched invisibly.

Worked with our own calculator

Wallpaper calculator

Given

Wall area (m²): 30
Roll length (m): 10
Roll width (m): 0.53
Waste (%): 15

Result

Rolls needed: 7

These figures are produced by the calculator below, not typed in by hand — they are recomputed whenever the tool changes.

Run it on your own figures →

Frequently asked questions

Do I subtract doors and windows?: You can leave small ones in as a safety margin; only subtract large openings, and even then keep a little extra for mistakes.
What is pattern repeat?: It's the vertical distance before the design repeats; a bigger repeat means more paper wasted when matching adjacent strips.
Why does batch number matter?: Colour can vary slightly between print runs, so rolls from different batches may show as faint bands on the wall.

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Sources

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