Wallpaper Roll Calculator
Turn wall sizes into wallpaper rolls and waste
Wallpaper roll planning FAQ
Why do I need both wall height and total width?
Wallpaper is hung as vertical drops from ceiling to skirting. The wall height decides how long each drop must be, and the total width tells you how many drops you need. Together they give the wall area and number of strips to cover, which is the basis of any roll estimate.
What is a pattern repeat and why does it matter?
The pattern repeat is how far you move down the roll before the design lines up again. For large florals or bold geometrics this can be 20 cm / 8 in or more. Each drop often needs to start on a repeat, so the calculator increases the usable length per drop when you enter a repeat, which usually means you get fewer full drops per roll and need more rolls overall.
Why is there a built-in allowance for waste?
Real rooms are not perfect rectangles. You lose paper when trimming at the ceiling and skirting, working around corners, sockets and windows and matching patterns. Instead of making you guess an allowance, this tool adds roughly 10% extra so most projects end up with a small spare margin rather than a frustrating shortfall.
How should I handle doors and big windows?
For a quick, safe estimate many decorators ignore openings and still allow for full wall area. If you want to be more precise, subtract the widths of large doors or windows from your total wall width before you type it in. Small windows and nooks are usually covered by the built-in waste allowance.
Can I mix different wallpapers in one calculation?
No. This calculator assumes one wallpaper design and one roll size for the whole area. If you are using different papers on different walls, run a separate calculation for each design, using only the wall widths covered by that paper.
What if my room has sloped ceilings or odd shapes?
Sloping ceilings, half-height walls and awkward recesses are best treated as separate rectangles. Work out the wall height and width for each section, add the widths together where they share the same height and run the calculator. When in doubt for complicated spaces, ask a professional hanger for a site visit and quote.
Is one spare roll really necessary?
A spare roll makes repairs much easier if the wall is damaged later or you mis-cut a drop. Many installers recommend ordering at least one extra roll, especially for patterned designs that might be hard to match by batch in future. The calculator’s waste allowance helps, but a spare roll is cheap insurance on a feature wall you love.
Does this work for murals or panelled wallpapers?
No. Murals and panel-style wallpapers are usually sold by panel size rather than traditional rolls, and the layout is fixed. Always follow the manufacturer’s instructions and use any dedicated mural calculator they provide instead of a generic roll estimate.
How to use this wallpaper roll calculator
This calculator turns a few simple measurements into a solid wallpaper order with drops, rolls and a built-in spare margin. The aim is to get you close enough that you can order confidently and avoid emergency last-minute rolls from a different batch.
1. Measure wall height and total width
Measure from finished floor to ceiling in the area you plan to paper, rounding up slightly if the ceiling is uneven. Then add together the widths of every wall to be covered. If you want to be conservative, leave doors and windows in; if you prefer a tighter number, subtract their widths before you type in the total.
2. Enter roll length and roll width from the label
Every wallpaper lists its roll length and width. In US mode, enter length in feet and width in inches. In metric mode, enter length in metres and width in centimetres. If you are not sure, check the product page or sample book before you order—using the wrong roll size can easily throw the math off.
3. Add the pattern repeat if your design has one
For simple textures or very small patterns you can leave repeat blank. For bold prints or large motifs, find the vertical repeat on the label (often in cm or inches) and enter it. The calculator then stretches each drop to the next full repeat and adds a little trim at the top and bottom, which usually means fewer usable drops per roll and therefore more rolls to order.
4. Read off drops, rolls and waste allowance
Tap Estimate rolls to see:
- Total wall area based on your height and width.
- Adjusted drop length including pattern repeat and trim.
- The approximate number of drops required and how many full drops you get per roll.
- How many rolls to order, rounded up so you don’t run short.
- An estimated spare percentage showing how much paper is available for waste and future touch-ups.
5. Copy the summary and check before you order
Use Copy summary to paste the numbers into your notes or email them to your decorator. Before buying, double-check that your measurements, roll size and pattern repeat match the exact wallpaper you are ordering. For expensive papers or very awkward rooms, ask your supplier or installer to confirm the quantities using their own tools as a final safety check.
Treat this tool as your quick maths helper so you can focus on colours, patterns and where the feature wall will look best, while the background numbers stay consistent and easy to share.
How the wallpaper roll calculator math works
Behind the scenes, this calculator follows the same steps professional wallpaper estimators use: work out the size of the walls, see how many full drops you can cut from a roll, then add a margin for waste and pattern matching.
1. Wall area from height and total width
First, your wall height and total width are converted into a single area:
Wall area = height × total width
This gives the square metres or square feet of wall to cover and is also used later to estimate what fraction of your total paper ends up as waste or spare.
2. Drop length with pattern repeat and trim
Wallpaper hangs in vertical strips (drops). The base drop length is your wall height plus a small extra for trimming at the top and bottom. If you enter a pattern repeat, the tool rounds this up to the next full repeat:
Base drop = wall height + trim allowance
Drop length = ceiling(Base drop ÷ pattern repeat) × pattern repeat
If you leave repeat blank, the calculator simply uses the base drop with the trim allowance.
3. Drops per roll and drops needed
Next, the calculator works out how many full drops you can cut from each roll:
Drops per roll = floor(roll length ÷ drop length)
Total drops needed comes from the wall width and roll width:
Drops needed = ceiling(total wall width ÷ roll width)
4. Rolls and spare percentage
To avoid being caught short, the calculator applies a simple waste margin to the drops needed, then divides by the drops per roll:
Drops with allowance ≈ drops needed × 1.10
Rolls needed = ceiling(drops with allowance ÷ drops per roll)
It also compares the total wall area with the total paper area in those rolls to estimate a spare percentage for offcuts and future repairs.
The end result is still an estimate, but a transparent one. You can sanity-check it with a handheld calculator, adjust your measurements, or take the summary to a decorator or supplier and ask them to confirm before you place the order.
References and further reading on wallpaper roll estimates
These guides explain the same measurement steps used in this calculator:
- Sherwin-Williams — How much wallpaper to buy — overview of roll coverage, pattern repeat and total area when planning wallpaper.
- Jane Clayton & Company — Wallpaper quantity calculator — calculator that also takes pattern repeat and trim into account.
Use this calculator together with the product label and, for tricky rooms, a quick check from a professional hanger or supplier before you commit to a final order.