Wallpaper Calculator

Enter the wall dimensions and ceiling height, the roll length and width, and the pattern repeat — the calculator works in whole drops, which is how wallpaper is actually hung.

Doors and windows are deducted, and a spare allowance is included.

How to use the wallpaper calculator

Enter the wall dimensions and ceiling height.

Add roll size and pattern repeat.

Read the number of rolls to buy.

Why use the Build Tally wallpaper calculator

Drop-based counting

Matches how wallpaper is really hung.

Pattern repeat handled

Straight and offset matches accounted for.

Openings deducted

Doors and windows come off the total.

Metric and imperial

Enter rolls in metres or feet.

Why rolls are counted in drops, not area

Wallpaper cannot be worked out by dividing wall area by roll area, because each strip has to run floor to ceiling in one piece. What matters is how many full drops you get from a roll: a standard European roll is 10.05 m long, so with a 2.4 m ceiling you get four drops per roll with a plain paper, and the remainder is offcut. This is why area-based estimates come out short, and why the calculator counts drops.

Pattern repeat changes everything

A patterned paper has to align across every seam, so each drop is cut to the next whole repeat rather than the exact wall height. With a 64 cm repeat and a 2.4 m ceiling, each drop is effectively cut at 2.56 m, and you may only get three drops per roll instead of four — a 25% increase in rolls from the pattern alone. Offset or drop-match patterns waste more again, because alternate drops start half a repeat down. Enter the repeat from the label and the calculator accounts for it.

Batch numbers and a spare roll

Every roll carries a batch number, and shade varies between batches enough to be visible on a wall. Buy all your rolls in one purchase with matching batch numbers, and check them before you start hanging. Keep one spare roll from the same batch — a damaged panel is an easy repair with matching paper and an expensive one without. If you are papering a feature wall only, measure that wall on its own rather than pro-rating the room total.

Read the guide: How Much Paint Do I Need? Gallons Per Room, Worked Out

Frequently asked questions

How many rolls of wallpaper do I need?

Count how many full drops you get from a roll, then how many drops the room needs. Enter your dimensions and repeat above and the calculator does it.

How long is a roll of wallpaper?

A standard European roll is about 10.05 m long and 53 cm wide. American rolls vary — check the label and enter the actual figures.

How does pattern repeat affect the number of rolls?

Each drop is cut to the next whole repeat, so a large repeat wastes more per drop and can add 20–30% to the roll count.

Should I subtract doors and windows?

Partially. The calculator deducts them, but you still need full drops above and below a window, so the saving is smaller than the raw area suggests.

Should I buy an extra roll?

Yes, from the same batch. Shading varies between batches and a matching spare makes future repairs straightforward.

Does the calculator handle feature walls?

Yes — enter just that wall's dimensions instead of the whole room.