📜 Interactive Wallpaper Calculator
Enter your total wall width and roll details to find the exact roll count required.
How to use the wallpaper calculator
- Add up the wall width: Measure each wall you want to cover and enter the total. For a feature wall, enter just that one wall. For a whole room, add all four walls together.
- Enter the wall height: Measure from the skirting board (baseboard) to the ceiling or to the top of a dado rail if you plan to stop there.
- Choose your unit: Feet, metres, inches or centimetres are all supported.
- Enter the roll details: These are printed on the wallpaper label or product page. A standard UK and European roll is 53 cm wide and 10 m long. Some wide or modern rolls differ, so always check.
- Enter the pattern repeat: This is the vertical distance before the design starts to repeat. Plain and textured papers have a repeat of 0. Patterned ones typically show 32 cm, 53 cm or 64 cm.
- Set your wastage: Ten percent covers trimming, mistakes and awkward corners. Increase it if the room has many corners, angles or a large pattern.
How the calculation works
Wallpaper is hung in vertical strips, so the calculation is really about strips rather than raw area. Here is the method our tool uses:
- Length of each strip = wall height + pattern repeat + 10 cm (extra for trimming at top and bottom)
- Strips per roll = roll length ÷ strip length, rounded down to a whole number (you cannot hang half a strip from a leftover piece)
- Strips needed = total wall width ÷ roll width, rounded up
- Rolls to buy = strips needed ÷ strips per roll × (1 + wastage %), rounded up
Rounding is the secret of accurate wallpaper maths. Because you round the strips per roll down and the rolls up, the result always leans toward buying slightly more, which is exactly what you want.
Worked example: a 4 m feature wall
Imagine a feature wall that is 4 m wide and 2.7 m high. You have chosen a roll that is 53 cm wide and 10 m long, with no pattern repeat, and you want 10% wastage.
| Step | Working | Result |
|---|---|---|
| Strip length | 2.7 + 0 + 0.1 m | 2.8 m |
| Strips per roll | 10 ÷ 2.8 = 3.57, round down | 3 strips |
| Strips needed | 4 ÷ 0.53 = 7.55, round up | 8 strips |
| Rolls with wastage | 8 ÷ 3 × 1.10 = 2.93, round up | 3 rolls |
Now see what a large pattern repeat does. If the same wall used a paper with a 64 cm repeat, each strip would need 2.7 + 0.64 + 0.1 = 3.44 m. Only two strips fit on a 10 m roll, so you would need 8 ÷ 2 × 1.10 = 4.4, which rounds up to 5 rolls. That is two more rolls for the very same wall, which is why the pattern repeat field matters so much.
Understanding pattern repeat and match types
A straight match pattern lines up horizontally across the strips, so each new strip starts at the same height as the previous one. A drop match (or half-drop) pattern lines up only when every second strip is shifted down by half the repeat, which uses more paper. If you are buying a drop-match design, add an extra 5 to 10 percent wastage. Random and textured papers, such as grasscloth effect or plain vinyl, do not need matching and waste the least.
Tips for ordering wallpaper
- Order everything at once: Rolls printed on different days can vary in shade. Check the batch number on each roll and make sure they match.
- Order one spare roll: A spare is inexpensive insurance against a miscut strip, a repair or a damaged patch years later.
- Do not deduct small windows: Small openings rarely save an entire strip, and the extra paper is useful for cutting around them.
- Deduct very large openings: For big glass doors or wide fireplaces, measure only the wall sections you will paper, and calculate those separately.
- Prepare the wall: Fill holes, sand rough areas and apply a lining paper or primer so the finish looks even and the paper comes off cleanly in the future.
- Pick the right paste: Use the adhesive recommended by the manufacturer. Paste-the-wall papers need a different approach from paste-the-paper types.
Common mistakes to avoid
Calculating by area alone: Dividing the wall area by the roll area ignores trimming and matching, and it usually leaves you a roll short. Counting strips is far more reliable.
Using the wrong roll size: American double rolls, European rolls and wide-width murals are all different. Always use the numbers shown by your supplier.
Skipping the test hang: Before you hang the whole room, hang one strip and check the colour and pattern in daylight and evening light.
Frequently asked questions
How many rolls of wallpaper do I need for a bedroom?
A medium bedroom of 3.5 m × 4 m with 2.5 m high walls (15 m of wall in total) needs about 11 rolls of standard 53 cm × 10 m paper with no pattern repeat, because each roll yields only three full-height strips. Enter your own measurements above for a closer figure.
Do I need to include doors and windows?
For quick estimates you can ignore them. If your openings are large, calculate only the wall you will cover. Our tool does not deduct openings on purpose, so the extra paper stays as a buffer.
What is a wallpaper double roll?
Some suppliers, especially in North America, sell double rolls that are twice as long as a single roll. Enter the actual length of the roll you receive, not the label name, to avoid confusion.
How much wastage should I allow?
Ten percent works for plain or small-pattern paper. For large patterns, drop matches or rooms with lots of corners, choose 15 percent.
Can I hang wallpaper on painted walls?
Yes, as long as the paint is sound and clean. Rough or glossy surfaces should be sanded and primed first so the paper sticks well.
How do I measure a sloping ceiling or a stairwell?
Measure the tallest point of each strip. Since strips are cut to the highest point and trimmed, using the maximum height keeps the calculation safe.
What to plan next
If you are still deciding on colours, try our colour palette generator to find shades that suit your wallpaper. Painting the remaining walls instead? Our paint calculator will tell you how much you need.