Wallpaper Calculator
Work out how many rolls of wallpaper you need for any room. Enter perimeter, wall height, pattern repeat and roll size for an instant rolls-to-buy estimate.
Updated 2026-06-14 · Free · No sign-up · Runs privately in your browser
Estimate rolls of wallpaper for a room. Works in feet/inches or meters — keep all inputs in the same units you pick.
Show the formula & steps
How the Wallpaper Calculator Works
Buying wallpaper is all about counting vertical strips and fitting them onto rolls. This calculator turns your room perimeter, wall height, pattern repeat and roll dimensions into the number of rolls to buy — accounting for pattern matching and a trim allowance so you don’t come up short mid-wall.
Keep every measurement in the same units (the calculator supports meters or feet) and it handles the rest.
The Formula
Strips needed = ⌈ room perimeter ÷ roll width ⌉ Cut length per strip = wall height + pattern repeat + 5% trim Drops per roll = ⌊ roll length ÷ cut length ⌋ Rolls to buy = ⌈ strips needed ÷ drops per roll ⌉
The brackets ⌈ ⌉ mean round up and ⌊ ⌋ mean round down — you can’t buy a fraction of a roll, and a partial drop won’t cover a full wall.
Worked Example
A room with a 16 m perimeter and 2.4 m walls, using rolls 10 m long × 0.53 m wide with a 0.5 m pattern repeat:
- Strips = ⌈ 16 ÷ 0.53 ⌉ = 31 strips
- Cut length = 2.4 + 0.5 + (5% trim ≈ 0.15) = 3.05 m
- Drops per roll = ⌊ 10 ÷ 3.05 ⌋ = 3 drops
- Rolls = ⌈ 31 ÷ 3 ⌉ = 11 rolls
Quick Roll Reference
| Roll length | Wall height | Cut length (no repeat) | Drops per roll |
|---|---|---|---|
| 10 m | 2.4 m | ~2.5 m | 4 |
| 10 m | 2.7 m | ~2.8 m | 3 |
| 10 m | 3.0 m | ~3.2 m | 3 |
Notice how a taller wall quickly drops you from four usable strips per roll to three, which can add several rolls to a large room. Always buy one spare roll from the same batch for repairs, and try the paint calculator or flooring calculator for the rest of your project — all part of our construction calculators hub.
Frequently asked questions
How many rolls of wallpaper do I need?+
First count the vertical strips around the room: divide the room perimeter by the roll width and round up. Then find how many full strips (drops) fit in one roll by dividing the roll length by the cut length (wall height plus pattern repeat plus a small trim). Divide strips by drops per roll and round up to get the number of rolls to buy.
What is a pattern repeat and why does it matter?+
The pattern repeat is the vertical distance before a wallpaper design starts again. To line patterns up at the seams you often waste up to one full repeat per strip, so a large repeat means longer cut lengths, fewer drops per roll and more rolls overall. Plain or random-match papers have a repeat of zero.
Should I subtract doors and windows?+
Only subtract whole strips you can genuinely skip. A standard door or large window may save one full strip; small windows usually save nothing because you still paper above and below them. Enter the number of strips you are confident you can omit in the 'strips to skip' box, and leave it at zero if unsure.
How much extra wallpaper should I allow for waste?+
This calculator already adds about 5% trim to each cut for the top and bottom. It is still wise to buy one extra roll, and to order all rolls from the same batch number so the color matches. Keep an offcut for future repairs.
What are standard wallpaper roll sizes?+
A common European roll is about 10 meters long and 0.53 meters wide. American rolls are often sold as double rolls roughly 27 inches wide. Always check the roll length and width printed on your wallpaper and enter those exact figures for an accurate result.