Wallpaper Calculator

Wallpaper Calculator works out how many rolls of wallpaper to buy, the way decorators count them: by drops. A drop is one full-height strip of paper. Each drop is cut a little longer than the wall — 10 cm extra for trimming at the top and bottom — and for a patterned paper it is rounded up to a whole number of pattern repeats, so the pattern meets across the joins. A roll gives as many whole drops as fit in its length; the rest is offcut. The walls need as many drops as roll widths fit across them. So enter the width of each wall you are papering, separated by commas, the wall height, the roll’s width and length (a standard roll is 0.53 m wide and 10.05 m long) and the pattern repeat from the label, and it gives the rolls to buy, the drop length, the drops per roll and how much is left over from each roll. Doors and windows are not subtracted, since the paper around them is cut from whole drops; that margin also covers mistakes.

1. Enter the widths of the walls you are papering and their height.
2. Enter the roll width and length (0.53 × 10.05 m is standard).
3. Enter the pattern repeat from the label (0 for plain).
4. Read the rolls to buy.

• For a drop pattern (the repeat offset by half), allow one extra roll.
• Ceilings and sloped walls are not covered.
• Buy every roll from one batch number; shades differ between batches.
• Everything is worked out in your browser. Nothing is sent anywhere.

For a 12 ft (3.66 m) wall, 9 ft high, with a plain standard roll: 7 drops, 3 per roll, so 3 rolls.

The height after which the pattern starts again, printed on the label. Each drop must start at the same point in the pattern.

Because a roll is cut into whole drops; the offcut left at the end of each roll is usually too short to use.

No: the paper around them is cut from whole drops, and the spare covers trimming mistakes.