Wallpaper Calculator
Calculate matched drop length, strips, drops per roll, whole rolls and cost from the dimensions printed on your wallpaper label.
Wallpaper roll formulas
Strips needed = total wall width ÷ roll width, rounded up.
Without a vertical repeat, cut length equals wall height plus trimming allowance. With a repeat:
Matched cut length = ceiling[(wall height + trim) ÷ repeat] × repeat.
Drops per roll = roll length ÷ matched cut length, rounded down.
Rolls before reserve = strips needed ÷ drops per roll, rounded up. Cost equals total rolls multiplied by the entered price.
Scope: this is a full-height vertical-strip estimate. Doors and windows are not automatically deducted because offcuts are not always reusable. Calculate walls of different heights separately. Confirm whether the product is sold as a single roll, double roll or bolt. Half-drop and offset matching can require a supplier-specific adjustment.
Six calculated examples
| Wall and roll assumptions | Calculated result |
|---|---|
| 12 × 8 ft; 20.5 in × 33 ft roll; no repeat; 4 in trim | 8 strips; 100 in cut; 3 drops/roll; 3 rolls |
| 12 × 8 ft; 20.5 in × 33 ft roll; 21 in repeat; 4 in trim | 8 strips; 105 in matched cut; 3 drops/roll; 3 rolls |
| 30 × 7.5 ft; 20.5 in × 33 ft roll; no repeat; 4 in trim | 18 strips; 94 in cut; 4 drops/roll; 5 rolls |
| 30 × 7.5 ft; 20.5 in × 33 ft roll; 25 in repeat; 4 in trim | 18 strips; 100 in matched cut; 3 drops/roll; 6 rolls |
| 10 × 2.4 m; 53 cm × 10 m roll; no repeat; 10 cm trim | 19 strips; 250 cm cut; 4 drops/roll; 5 rolls |
| 10 × 2.4 m; 53 cm × 10 m roll; 64 cm repeat; 10 cm trim | 19 strips; 256 cm matched cut; 3 drops/roll; 7 rolls |
How to use the calculator
- Add the widths of walls that share one height, without overlapping measurements.
- Copy the packaged roll width, length and vertical repeat; roll sizes are not universal.
- Enter the total top-and-bottom trimming allowance per strip.
- Use zero repeat only for random/no-match wallpaper. Enter the stated repeat for a straight match.
- Calculate different wall heights separately. Add reserve rolls only when you deliberately want sealed material from the same dye lot.
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- Square Footage Calculator for wall and room areas.
- Paint Calculator for an alternative wall finish.
- Tile Calculator for tiled wall coverage.
- Drywall Calculator for wallboard sheets and cost.