How many rolls you really need
Wallpaper is hung in vertical strips, so the count starts from how many strips fit across your wall: total wall width divided by the roll's width, rounded up. Each strip has to be as tall as the wall, so the number of strips you get from one roll is the roll length divided by that drop height, rounded down. Divide the strips you need by the strips per roll and round up, and you have the rolls to buy.
Why pattern repeat matters
If the design repeats, each strip has to be cut so the pattern lines up with its neighbour, which wastes a little at the top of every drop. Adding the repeat to the drop height accounts for that waste — a large repeat can noticeably increase the rolls needed, which is why it's a separate field here.
Buy a little extra
It's normal to buy one more roll than the strict minimum, both for mistakes and so any future repair comes from the same batch and colour. Measure the total width of every wall you're papering, subtracting large openings only if they're floor-to-ceiling.
Frequently asked questions
What is a standard roll size?
A common European roll is about 53 cm wide and 10 m long, but sizes vary. Enter the figures printed on your roll for an accurate count.
Should I subtract doors and windows?
Only for very large openings. Small ones are usually ignored because the offcuts around them rarely make a full extra strip and it's safer to have a little spare.
How much wallpaper do I need?
Measure the wall area, subtract large openings, and divide by the usable area per roll, adding about 10–15% for pattern matching and trimming.
How do I account for pattern repeat?
A large repeat wastes more paper, since each strip must line up with the last. Bigger repeats need more rolls, which the tool factors in.
Should I buy an extra roll?
Yes — buy a little extra from the same batch. Later batches can differ slightly in colour, and you'll want matching paper for repairs.