Wallpaper is hung in vertical strips, so the useful number is how many full-height strips you can cut from each roll – a large pattern repeat can waste a third of every roll. U.S. double rolls are about 20½ in × 33 ft; European rolls are 53 cm × 10.05 m. Buy all rolls from the same batch number.
How to use the Wallpaper Calculator
- Room length
- Room width
- Wall height
- Doors (3 ft wide)
- Windows (3 ft wide)
- Roll size
- Pattern repeat
- Waste
- Price per roll
Results update as you type, and every field accepts the units shown in its menu.
How it works
Enter the room length, width and height, the number of doors and windows, the roll size, pattern repeat, waste and price per roll.
Tips for an accurate estimate
- Take measurements at floor level and at the ceiling – walls and rooms are often slightly out of square.
- Use the manufacturer’s coverage, spacing and installation data when it differs from the typical values here.
- Keep a little extra of every finish material for touch-ups and repairs later.
- Check local building codes and permits before structural, electrical, plumbing or gas work.
Common mistakes to avoid
- Sizing heating or cooling equipment by area alone when insulation, windows and climate make a big difference.
- Buying too little paint, stain or flooring and ending up with mismatched batches.
- Overlooking the extra material for steps, railings, gables and trim.
Inputs explained
| Field | What to enter |
|---|---|
| Room length | Units: ft, m, in, yd, cm |
| Room width | Units: ft, m, in, yd, cm |
| Wall height | Units: ft, m, in, yd, cm |
| Doors (3 ft wide) | A number |
| Windows (3 ft wide) | A number |
| Roll size | Choose one: US double roll 20.5 in × 33 ft, European roll 0.53 × 10.05 m, Wide roll 27 in × 27 ft, Wide roll 0.70 × 10.05 m … |
| Pattern repeat | Units: in, cm, mm, ft, m |
| Waste | In % |
| Price per roll | Units: /piece |
What each result means
- Net wall area = max(2×([Room length] + [Room width])×[Wall height] – [Doors (3 ft wide)]×1.9509638400000002 – [Windows (3 ft wide)]×1.3935456000000002, 0)
- Strips per roll = floor([Roll length]÷([Wall height] + [Pattern repeat] + 0.1016))
- Strips needed = ceil(max(2×([Room length] + [Room width]) – [Doors (3 ft wide)]×0.9144 – [Windows (3 ft wide)]×0.9144÷2, 0)÷[Roll width] – 0.000001)
- Rolls = ceil([Strips needed]÷[Strips per roll]×(1 + [Waste]÷100))
- Cost = [Rolls]×[Price per roll]
Example values
How the main result changes when Room length changes and everything else stays at the example values above:
| Room length (ft) | Rolls |
|---|---|
| 7 | 7 |
| 10.5 | 9 |
| 14 | 10 |
| 17.5 | 12 |
| 21 | 14 |
| 28 | 17 |
Formula
Strip length = wall height + pattern repeat + 4 in trimStrips per roll = floor(roll length ÷ strip length)Strips needed = ceil(net wall width ÷ roll width)Rolls = ceil(strips ÷ strips per roll × (1 + waste))Worked example
Inputs — Room length: 14 ft; Room width: 12 ft; Wall height: 8 ft; Doors (3 ft wide): 1; Windows (3 ft wide): 2; Roll size: US double roll 20.5 in × 33 ft; Pattern repeat: 0 in; Waste: 10 %; Price per roll: $45 /piece.
Results — Net wall area = 365 ft²; Strips per roll = 3; Strips needed = 27; Rolls = 10; Cost = $450.00.
Frequently asked questions
How many rolls of wallpaper for a 12 × 14 room?
With 8 ft walls and a US double roll, about 9–10 rolls for a plain paper; more with a large pattern repeat.
What is a pattern repeat?
The vertical distance before the pattern repeats; each strip must be cut to match, which adds waste.
Should I subtract windows?
Subtract doors fully and windows roughly by half, because you still need short strips above and below them.
What formula does the Wallpaper Calculator use?
Strip length = wall height + pattern repeat + 4 in trim.