Wallpaper Calculator
How Much Wallpaper Do I Need?
The formula below is the same one professional decorators use — or skip the maths and get an instant, exact roll count from the planner itself.
Open the wallpaper planner1. Measure each wall
Note the width of each wall on its own, not just the total perimeter — wallpaper is hung wall by wall, not wrapped continuously around the corners.
2. Round each wall up to a whole strip
Divide each wall's width by your roll's width (usually 53cm) and round up — a leftover sliver at the end of a wall still costs a full strip. Add the walls together, then subtract a strip or two for large doors and windows.
3. Work out strips per roll
Divide roll length (usually just over 10m) by your wall height plus a trim allowance and any pattern repeat.
| Wall (width × height) | Plain paper | 64 cm repeat |
|---|---|---|
| 3.0 m × 2.4 m | 2 rolls | 2 rolls |
| 4.0 m × 2.4 m | 2 rolls | 3 rolls |
| 5.0 m × 2.6 m | 4 rolls | 4 rolls |
Standard 0.53 × 10.05 m roll, before the recommended +1 spare roll. Large-scale 2026 patterns typically waste 25–35% of each roll on pattern matching, compared with 10–15% for plain or textured paper.
Common questions
Do I need extra for a patterned wallpaper?
Yes — patterns with a repeat distance waste more per strip since you have to line up the design. The planner has a pattern-repeat field built in for exactly this.
What's a standard roll size?
Most European rolls are 53cm wide and just over 10 metres long. Always check the label — US rolls and specialty/mural rolls vary, and the planner accepts any size.
Should I round up or down?
Always round up. Running one roll short mid-job risks a dye-lot mismatch if you have to buy more later — the planner rounds up for you automatically.
How much extra wallpaper should I buy for waste?
Plan for 10–15% waste with plain or free-match paper, 15–20% with a small repeat (under 27 cm), and 25–35% with a large repeat (53 cm or more), then add one spare roll from the same batch number.
Planning a specific room?
Jump straight to what to expect for your room type.
Estimating for a client job instead? Try the contractor estimator →
Planning more than the formula? Draw your walls and get the exact cutting plan, workbench sheets and order list — free to start.
Get My Cutting PlanWant to know the cost before you draw? See plans & pricing →