How much wallpaper do I need?
Installers count strips, not square feet. Each strip is cut to the wall height plus one pattern repeat plus a few inches to trim. Work out how many strips one roll gives, how many strips the walls need, and divide.
Strips per roll = roll length ÷ (wall height + repeat + trim), rounded down
Rolls = (wall width ÷ roll width, rounded up) ÷ strips per roll, rounded up
Take a wall 12 ft wide and 8 ft high, a 20.5 in × 33 ft double roll and a 21 in repeat. Each strip is 96 + 21 + 4 = 121 in. The roll is 396 in long, and 396 ÷ 121 = 3.27, so 3 strips per roll. The wall is 144 in wide, and 144 ÷ 20.5 = 7.02, so 8 strips. 8 ÷ 3 = 2.67, so 3 rolls. By area alone (96 sq ft ÷ 56 sq ft per roll) you'd buy 2 and run short.
| Roll | Width | Length | Area |
|---|---|---|---|
| Double roll | 20.5 in | 33 ft | 56 sq ft |
| Double roll | 27 in | 27 ft | 61 sq ft |
| European roll | 53 cm (20.9 in) | 10.05 m (33 ft) | 57 sq ft |
| Single roll | 20.5 in | 16.5 ft | 28 sq ft |
| Wide roll | 36 in | 24 ft | 72 sq ft |
In the US, wallpaper is often priced per single roll but sold in double rolls. Check the label for the actual size and enter it.
Wallpaper calculator with repeat
The pattern repeat is the distance before the design starts again, printed on the label. A random match or plain paper has no repeat; enter 0. For a straight or half-drop match, the calculator adds the full repeat to every strip, which is the safe choice.
The repeat matters most when it pushes a strip past what the roll can fit. On a 9 ft wall, a 21 in repeat makes each strip 133 in, so a 33 ft roll gives only 2 strips instead of 3. A 12 ft wall then takes 4 rolls instead of 3.
Wallpaper calculator in inches
Roll width, roll length and repeat are entered separately from the walls, so you can use inches for the paper and feet and inches for the walls. For metric labels, divide centimeters by 2.54: a 64 cm repeat is 25.2 in, and a 53 cm roll is 20.9 in wide.
Whole rooms, doors and windows
Add each wall. Walls of the same height count as one run, because the piece left at a corner carries onto the next wall. A 12 × 12 ft room with 8 ft walls is 576 in around: 29 strips, or 10 double rolls with a 21 in repeat.
Enter doors and windows in square feet. The calculator takes them off as full-height width: a 3 × 7 ft door on an 8 ft wall saves 21 ÷ 8 = 2.6 ft. The short pieces above and below come from roll ends. With a large repeat, leave openings at 0 for a safer count.
Pricing a wallpaper job
Paperhangers often price per roll or per strip, plus wall prep: stripping old paper, skim coating and priming. Use contractor mode to add labor and markup, then send it with the painting estimate template.
Questions
How many rolls of wallpaper do I need for a 12 × 12 room?
With 8 ft walls, 20.5 in × 33 ft double rolls and a 21 in repeat, about 10 rolls before taking out doors and windows. A different roll size or repeat changes the count.
What is a pattern repeat?
The vertical distance before the design starts again. It's printed on the label, and each strip needs that much extra so the pattern lines up.
What is a double roll of wallpaper?
Two single rolls on one bolt, typically 20.5 in × 33 ft or 27 in × 27 ft in the US. Many US papers are priced per single roll but sold only in double rolls.
Should I buy an extra roll of wallpaper?
Many installers do. A roll from a later batch can differ in color, so buying one spare with the order is the easiest way to have a match for repairs.