Wallpaper is sold by the roll, but walls are measured in strips — and that mismatch is why so many people buy too few rolls, or far too many. This free wallpaper calculator works it out properly: enter your wall size and roll size, add the pattern repeat if your paper has one, and it tells you exactly how many strips you need and how many rolls to buy.
Wallpaper Calculator
Add together the widths of every wall you plan to paper. For one wall, just enter that wall's width.
A standard roll is about 20.5 inches (53 cm) wide. Check the label on your roll.
A standard roll is about 33 feet (10 metres) long. Check the label on your roll.
Patterned paper wastes some length on every strip so the pattern lines up. The repeat is printed on the roll label. Plain paper has a repeat of 0.
How to use it
- Measure the width of every wall you plan to paper and add them together — that is your total wall width in feet.
- Measure the wall height from floor to ceiling in feet. If the height varies, use the tallest height so no strip comes up short.
- Enter your roll's width and length from its label. The defaults (20.5 inches wide, 33 feet long) fit most standard rolls.
- If your paper has a pattern, enter the pattern repeat in inches from the label. For plain paper, leave it at 0.
- Press Calculate and buy the full number of rolls shown — never round down, or the last strip may come from a different batch.
Worked example
Walls totalling 40 feet wide and 8 feet high need 24 strips of a standard 20.5-inch roll. Each 33-foot roll gives 4 strips (33 feet ÷ 8 feet per strip), so you need 6 rolls. With a 12-inch pattern repeat, each strip effectively needs 9 feet, so a roll gives only 3 strips — and the same walls need 8 rolls.
Tips before you buy
- Always buy one spare roll if you can: a later batch can differ slightly in shade, and a spare roll is cheap insurance against a torn strip.
- Do not subtract doors and windows from your measurements — the offcuts around them are rarely usable as full strips, so counting them keeps you safe.
- Check the batch number on every roll before you start. Rolls from different batches can look different on the wall.
- Measure around the whole room, not just one wall, if you plan to paper the full room.
Frequently asked questions
What is a pattern repeat?
The vertical distance before the pattern starts again. Every strip must be cut longer by up to one repeat so the pattern lines up with the strip beside it.
Should I subtract doors and windows?
No. The strips beside a door or window are still cut at full height, and the small offcuts are usually unusable, so keep them in your total.
What if my roll is in centimetres and metres?
Convert first: 1 inch = 2.54 cm and 1 foot = 0.3048 metres. A 53 cm × 10 m roll is about 20.5 inches × 33 feet.