Wallpaper Calculator (Rolls Needed with Pattern Repeat)

Wallpaper is cut into drops the height of the wall, and each roll yields only a whole number of them, so square-footage estimates come up short. This calculator counts the strips around the room, works out the drop length including the pattern repeat, finds how many drops a roll gives, and tells you how many rolls to buy plus a spare. American and metric single and double rolls are built in, or enter your own roll size.

Wallpaper rolls calculator

How it works

Strips = room perimeter ÷ roll width, rounded up
Drop length = wall height + 4 in for trimming, rounded up to a whole pattern repeat
Drops per roll = roll length ÷ drop length, rounded down
Rolls = strips ÷ drops per roll, rounded up, plus spares

American rolls are 27 in wide (single about 13.5 ft, double 27 ft); metric rolls 20.5 in wide (single 16.5 ft, double 33 ft). Most paper is sold as double rolls.

Worked example

A 14 × 12 ft room with 8 ft walls, one door and two windows, papered with a random-match American double roll:

Room length: 14 ft
Room width: 12 ft
Wall height to paper: 8 ft
Doors: 1
Windows: 2
Roll: American double roll: 27 in × 27 ft (about 60 sq ft)
Pattern repeat: 0 in
Extra rolls for mistakes and future repairs: 1

The calculator gives:

Rolls to buy: 9 (8 + 1 spare)
Strips (drops) needed: 24 at 27 in wide around 52 ft of wall
Drop length: 100 in each (96 in wall + 4 in trim)
Drops per roll: 3 from a 27 ft roll
Wall area: 366 sq ft net of openings (416 gross)

The 52 ft perimeter needs 24 strips of 27 in paper. Each drop is 100 in (96 + 4 for trim), so a 27 ft roll gives three drops: eight rolls plus one spare, nine in all. Pieces over the door and windows come from the offcuts of full drops, which is why the openings do not reduce the roll count. An 18 in repeat rounds the drop up to 108 in, still three drops from a double roll; a metric single roll (16.5 ft) gives only one full drop per roll at this wall height, so the same room takes 32 of them.

Material and waste notes

Random-match papers waste the least; straight-match papers waste up to one repeat per drop, drop-match half a repeat if you cut alternately from two rolls.
Roll sizes vary by maker and country; use the custom option with the label figures.
Buy all rolls from one batch (dye lot) and check the numbers on every roll.
Ceilings, borders and feature walls with a different paper are separate calculations.
Wallpaper paste, sizing and lining paper are extra; heavy vinyls may need lining paper on rough walls.

Frequently asked questions

How many rolls of wallpaper for a 12×12 room?

With 8 ft walls and an American double roll, 22 strips at 3 drops per roll: 8 rolls plus a spare. Pattern repeat can change that.

How many square feet does a double roll of wallpaper cover?

About 60 sq ft for an American double roll and 56 for a metric one, but only whole drops count, so plan on 70 to 80% of that.

Do I subtract windows and doors from wallpaper?

Not for counting rolls: the pieces over and around openings are cut from full-height drops. Only very large openings (a wall of glass) save a strip.

What does pattern repeat mean for wallpaper?

The distance before the design repeats down the roll. Each drop has to start at the same point in the pattern, so the drop length rounds up to a whole repeat and the waste grows with the repeat.

Single roll or double roll?

Paper is priced by the single roll but sold as double rolls (two singles’ length in one roll). This calculator uses the roll you actually get.

Sources

Wallpaper Boulevard, "Single vs double roll": American rolls 27 in wide, single about 13.5 ft, double 27 ft; metric rolls 20.5 in wide, single 16.5 ft, double 33 ft

Last reviewed: 26 September 2026. The calculation is covered by automated tests with known answers taken from the sources above. Found an error? Please let us know.