How this calculator works
Wallpaper goes up in vertical strips called drops. The number of drops is the total width of the walls divided by the width of the roll, rounded up. Each drop is as long as the wall height, plus the pattern repeat (so the pattern can be matched along the join) and a few centimetres to trim at the top and bottom. Divide the roll length by the drop length to see how many drops one roll gives, and then how many rolls you need.
Worked example: a room with 14 m of walls, 2.4 m high, and a standard 0.53 × 10.05 m roll. 14 ÷ 0.53 = 26.4, so 27 drops. Each drop is 2.4 + 0.1 = 2.5 m, so a roll gives 4 drops, and you need 7 rolls. With a 32 cm pattern repeat each drop is 2.82 m long, so a roll gives only 3 drops, and you need 9 rolls.
Tips before you buy
- Check the pattern repeat and the match type on the label. A drop match (where the pattern steps down) wastes more than a straight match, so it is worth checking with the supplier.
- Buy all your rolls from the same batch number: shades can vary between batches, and a later roll may not match.
- Buy one extra roll for repairs. A wallpaper that is discontinued or from a different batch is hard to match.
- Hang the first drop against a plumb line, not the corner or the ceiling, because walls and ceilings are rarely straight.
- Allow the paste to soak in for the time on the packet before hanging, or use paste-the-wall paper to skip that step.
Tools & materials for this project
As an Amazon Associate we earn from qualifying purchases. These links do not change what you pay.
Frequently asked questions
How many rolls of wallpaper do I need for a 4m x 3m room?
About 7 rolls of standard 10.05 × 0.53 m paper for a room 2.4 m high with a plain or random pattern, and 9 rolls with a 32 cm pattern repeat.
How long is a standard roll of wallpaper in the UK?
10.05 m long and 0.53 m wide, which is about 5.3 m². Wider and longer rolls are sold, so check the label.
Do I take off windows and doors when I calculate wallpaper?
No, not when you count drops. You still need full drops either side of the opening and short drops above and below it. Only on a plain paper, with a lot of openings, can you save a roll.
How much extra wallpaper should I buy?
The calculation allows for the pattern repeat and trimming. Add one spare roll from the same batch for repairs or mistakes.
Add this calculator to your website
Running a blog, a contractor site or a class page? You can put this calculator on it for free. Copy the code below, and please leave the link underneath the calculator in place. The small script just resizes the frame to fit the results; if your site strips scripts, the calculator still works inside a scrolling frame.
Related calculators & guides
Estimates only. Results assume standard materials and simple shapes. Supplier products vary, and the final call on quantity, structure and safety is yours. Check your local code and your supplier's guidance before ordering.