How to use the wallpaper calculator
- Measure the walls. For a whole room enter the floor length and width; for an accent wall, enter that wall's width. Enter the height from baseboard to ceiling.
- Count the doors. Each standard door removes about 3 feet of wall width from the strips needed.
- Enter the roll size. A standard US double roll is about 20.5 inches wide and 33 feet long. European rolls are usually 0.53 m by 10 m, about 21 inches by 33 feet. Always use the size printed on your label.
- Enter the pattern repeat. It is printed on the label. Matching the pattern wastes part of every strip, so larger repeats mean more rolls.
The strip method
Strip length = wall height (in) + pattern repeat
Strips per roll = roll length (in) ÷ strip length, rounded down
Rolls = strips ÷ strips per roll, rounded up
Installers count whole strips because the leftover piece at the end of a roll is usually too short for another full-height strip.
Worked example
A 14 × 12 ft room has 52 feet of wall. Subtract one door (3 ft) for 49 feet, which needs 29 strips of 20.5 inch paper. With 8 ft walls and no pattern repeat, each 33 ft roll gives 4 strips, so buy 8 rolls. With a 21 inch pattern repeat, each strip is 117 inches and a roll gives only 3 strips, so you need 10 rolls.
Tips for buying and hanging
- Buy from one batch (lot number). Colors can vary slightly between print runs.
- Add one roll for mistakes, tricky corners and future repairs.
- Prime the walls with a wallpaper primer so the paper sticks and comes off cleanly later.
- Peel-and-stick paper often comes in smaller rolls; check the coverage on the label and enter its size above.
Painting the other walls? Use the paint calculator for the same room.
Frequently asked questions
How many rolls of wallpaper do I need for a 12x12 room?
A 12 × 12 ft room with 8 ft walls and one door has 45 feet of wall to cover, about 27 strips of 20.5 inch paper. With no pattern repeat that is 7 double rolls; with a large repeat it can be 9 or more.
How much does a roll of wallpaper cover?
A standard US double roll (20.5 in × 33 ft) covers about 56 square feet in theory, but only about 44 to 50 square feet in practice after trimming and pattern matching.
What is a pattern repeat?
The vertical distance before the design repeats. You must line up the pattern across strips, so each strip uses the wall height plus up to one repeat of extra paper.
Should I subtract windows when calculating wallpaper?
Usually not. The wall above and below a window still needs paper, and the cut-outs are rarely reusable. Subtract only full-height openings like doors.
How many rolls for an accent wall?
Measure the width and height of that wall. A 12 ft wide, 8 ft tall wall needs 8 strips of 20.5 inch paper, which is 2 double rolls with no pattern repeat.
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Last updated October 2026.