Why wallpaper is counted in strips
Dividing wall area by the square footage on the label almost always comes up short. Wallpaper is hung in vertical strips, each cut a little longer than the wall and matched to the pattern, and the leftover at the end of each roll is usually too short for another full strip. The strip method used here, the same one paperhangers use, counts how many full-height strips you need and how many you can cut from each roll.
- Cut length. Wall height plus a trim allowance (4 in is standard: 2 in at the ceiling, 2 in at the baseboard), rounded up to a whole number of pattern repeats so every strip starts at the same point in the design.
- Strips per roll. Roll length divided by cut length, rounded down.
- Strips needed. Wall width divided by roll width, rounded up. Doors remove 3 ft of width each; windows remove 1.5 ft, because the space above and below still needs short pieces.
- Rolls. Strips needed divided by strips per roll, rounded up.
The formula
strips per roll = roll length ÷ cut length, rounded down
strips needed = (wall width − 3 ft × doors − 1.5 ft × windows) ÷ roll width, rounded up
rolls = strips needed ÷ strips per roll, rounded up
A common shortcut is strips per roll = roll length ÷ (height + repeat). It gives the same or a slightly more cautious answer, and is a good sanity check if you don't know the exact repeat.
Example: a 12 × 12 ft bedroom
Four 12 ft walls (48 ft total), 8 ft high, one door and two windows, standard US double rolls (20.5 in × 33 ft) with a 21 in repeat and 4 in trim allowance, at $50 per double roll.
| Step | Result |
|---|---|
| Cut length (96 + 4 = 100 in, rounded up to 5 × 21 in) | 105 in (8 ft 9 in) |
| Strips per roll (396 in ÷ 105 = 3.77) | 3 |
| Width to cover (48 − 3 − 3) | 42 ft |
| Strips needed (504 in ÷ 20.5 = 24.6) | 25 |
| Rolls (25 ÷ 3 = 8.3) | 9 rolls |
| Estimated cost (9 × $50) | $450.00 |
With a plain paper (repeat 0), each strip is 100 in, a roll yields 3 strips (3.96 rounded down) and you still need 9 rolls. Set the trim to 0 as well and a roll seems to give 4 strips of exactly 96 in, cutting the order to 7 rolls, but with no margin for an uneven ceiling you'd likely run short. Keep the trim allowance.
Typical roll sizes
| Type | Width | Length | Area |
|---|---|---|---|
| US double roll | 20.5–21 in | 33 ft | ≈ 56 sq ft |
| US single roll | 20.5–21 in | 16.5 ft | ≈ 28 sq ft |
| Euro roll | 20.5 in | 33 ft | ≈ 56 sq ft |
| Wide / commercial | 27 in | 27 ft | ≈ 61 sq ft |
Tips before you order
- Check how it's priced. Many US retailers quote a single-roll price but ship only double rolls. Enter the price for the roll length you entered.
- Watch for half-drop matches. On a half-drop pattern every other strip starts half a repeat lower; adding half the repeat to the trim allowance covers it.
- Buy one batch, plus one. Rolls from different print runs can differ in shade. An extra roll is cheaper than a mismatched wall.
- Measure each wall. Add widths rather than using the room perimeter if you are skipping an accent wall or a wall of built-ins.
Frequently asked questions
How big is a roll of wallpaper?
Most American wallpaper is about 20.5 to 21 inches wide and sold in double rolls about 33 feet long, roughly 56 square feet. A single roll is half that length. European rolls are usually 20.5 inches by about 33 feet as a single roll, and many designer papers are 27 inches wide. Always enter the size on the label.
Why is wallpaper priced per single roll but sold in double rolls?
It is an industry habit. Many American wallpapers are quoted per single roll but only shipped as double rolls, so a listing of 45 dollars per roll can mean 90 dollars per double roll you actually receive. Enter the price of the roll length you entered above.
What is a pattern repeat?
The repeat is the vertical distance before the design starts again, printed on the label as a number in inches. To line strips up, each one has to start at the same point in the pattern, so every strip is cut to a multiple of the repeat. Large repeats waste more paper per strip.
Should I subtract doors and windows for wallpaper?
Only partly. A door takes out close to a full strip width, but windows still need short pieces above and below, and those rarely come entirely from scraps. This calculator removes 3 feet of width per door and 1.5 feet per window.
How many extra rolls of wallpaper should I buy?
Buy at least one roll more than the calculated number if the room has lots of corners, or if you are new to hanging paper. Order every roll from the same print run, called the batch or dye lot, because a later batch may not match in color.
Rates and figures last checked September 2026.
This calculator gives estimates for planning. Check current rates and product labels before you buy, list or file.