Wallpaper calculator
Wallpaper is bought in whole rolls and cut in whole drops. A pattern repeat wastes part of every drop, and the waste is not proportional.
Rolls needed
8
- Drops to hang
- 32
- Drops per roll
- 4
- Cut length per drop
- 2.400
- Waste from pattern matching
- 0.00
- Wall area
- 43.20
- Area per roll
- 5.33
Show the working
- Room perimeter = 18
- Wall height = 2.4
- Roll length = 10.05
- Roll width = 530
- Pattern repeat = 0
- Doors and windows = 2
- Cut length per drop = 0 > 0 ? ceil(2.4 * 1000 / 0) * 0 / 1000 : 2.4 = 2.4
- Drops to hang = ceil((18 * 1000 / 530)) - 2 = 32
- Drops per roll = floor(10.05 / 2.4) = 4
- Rolls needed = 4 > 0 ? ceil(32 / 4) : 0 = 8
- waste_per_drop = 2.4 - 2.4 = 0
- Waste from pattern matching = 0 * 32 = 0
- Wall area = 18 * 2.4 = 43.2
- Area per roll = 10.05 * 530 / 1000 = 5.3265
Values are shown to six significant figures here; the arithmetic itself runs on exact fractions and is only rounded where a number is printed.
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The formula
- cut length = ceil(wall height / pattern repeat) x repeat
- drops per roll = floor(roll length / cut length)
Buy every roll from the same batch. Colour varies between print runs and the difference shows on a wall.
A large repeat can cut usable drops per roll from four to three, adding a third to the cost.