Wallpaper Calculator
Work out how many rolls of wallpaper you need from the wall width and height, the roll size and the pattern repeat, with strips per roll and a spare.
Results
| Item | Value |
|---|
Quick Answer
Rolls = strips needed ÷ strips per roll, rounded up. For 40 ft of wall, 8 ft high, minus 6 ft of doors and windows, with 20.5 in × 33 ft rolls and no pattern repeat, you need 20 strips at 3 strips per roll, so 7 rolls plus 1 spare = 8.
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Table of Contents
- Wallpaper Calculator
- Quick Answer
- Related Calculators
- How This Wallpaper Calculator Works
- How to Use the Wallpaper Calculator
- Core Formulas
- Key Terms
- Worked Example
- Real-Life Examples
- Strip Method vs Area Method
- Strips per Roll by Wall Height
- What Changes How Many Rolls You Need
- Common Mistakes to Avoid
- Frequently Asked Questions
- References & Sources
How This Wallpaper Calculator Works
Measure the total width of the walls you want to cover and their height. Subtract the width of doors and large windows. Enter your roll width, roll length and the pattern repeat from the label. The calculator works out how long each strip must be, how many strips fit on one roll, how many strips cover the walls, and the number of rolls to buy, plus spares.
Quick explanation: wallpaper is hung in vertical strips.
- Strip length: wall height plus extra for trimming.
- Pattern repeat: makes each strip longer so the pattern lines up.
- Leftover pieces: short offcuts often cannot be used, so count whole strips.
How to Use the Wallpaper Calculator
- Add up the width of every wall you will paper.
- Measure the wall height and the width of doors and large windows.
- Enter the roll width, length and pattern repeat from the label.
- Choose how many spare rolls you want.
- Press Calculate and read the rolls to buy.
Core Formulas
- Strip length: wall height + 4 in, rounded up to a whole pattern repeat
- Strips per roll: roll length ÷ strip length, rounded down
- Strips needed: (wall width − openings) ÷ roll width, rounded up
- Rolls: strips needed ÷ strips per roll, rounded up, plus spares
Key Terms
- Pattern repeat: the vertical distance before the pattern starts again.
- Drop: the length of one strip.
- Dye lot: a production batch. Rolls from one lot match in color.
- Double roll: a roll sold as two single rolls joined, common in the US.
- Trim allowance: extra length cut off at the ceiling and baseboard.
Worked Example
The same room with a 21-inch pattern repeat.
- Strip length = 96 + 4 = 100 in, rounded up to 5 repeats = 105 in
- Strips per roll = 396 ÷ 105 = 3, and strips needed = 34 ft × 12 ÷ 20.5 = 20
- Rolls = 20 ÷ 3, rounded up to 7, plus 1 spare = 8
Real-Life Examples
- Accent wall: one 12 ft wall, 8 ft high, needs 4 rolls with a spare.
- Bedroom: a 12 × 14 ft room (52 ft of wall) with 6 ft of openings needs 10 rolls with a spare.
- Tall ceilings: at 10 ft high, the same bedroom needs 10 rolls.
- Big patterns: a 25-inch repeat can add a roll or more to the order.
Strip Method vs Area Method
- Area method: wall area ÷ roll area. Quick, but it ignores offcuts and pattern matching.
- Strip method: counts whole strips, so it is more realistic and usually needs more rolls.
- This calculator: uses the strip method.
Strips per Roll by Wall Height
For a 33 ft roll, with 4 in added to each strip for trimming.
| Wall height | No repeat | 12 in repeat | 21 in repeat | 25 in repeat |
|---|---|---|---|---|
| 7 ft | 4 | 4 | 3 | 3 |
| 8 ft | 3 | 3 | 3 | 3 |
| 9 ft | 3 | 3 | 3 | 3 |
| 10 ft | 3 | 3 | 3 | 3 |
| 12 ft | 2 | 2 | 2 | 2 |
What Changes How Many Rolls You Need
- Pattern repeat: large repeats waste more paper per strip.
- Ceiling height: taller walls mean fewer strips per roll.
- Roll size: US and European rolls differ, so read the label.
- Room shape: many corners, niches and openings add waste.
Common Mistakes to Avoid
- Using area only. It underestimates rolls when there is a pattern repeat.
- Forgetting trim allowance. Each strip needs extra at the top and bottom.
- Buying from different batches. Colors can vary between dye lots.
- Skipping a spare roll. It helps with mistakes and future repairs.
- Subtracting small windows. Paper around them is often wasted anyway.
Frequently Asked Questions
Divide the strips needed by strips per roll and round up. Add one spare.
Add the widths of all walls, measure the height, and subtract wide doors and windows.
The distance before the pattern repeats. It is printed on the label.
At least one spare roll from the same batch.
It varies. Check the label for the width and length.
Subtract doors and large windows. Small windows usually waste the paper around them anyway.
Each strip must start at the same point in the pattern, which wastes some paper.
A pattern that lines up half a repeat lower on the next strip. It can add waste.
Yes. Treat it as a wall with width equal to the room width and height equal to the room length.
Enter your price per roll to get the total.
It is a rough guide, but it ignores offcuts. The strip method is more accurate.
Yes. The batch number keeps colors consistent.
References & Sources
| Source | Used For | Link |
|---|---|---|
| Wikipedia, Wallpaper | Wallpaper types, hanging and pattern matching. | https://en.wikipedia.org/wiki/Wallpaper |