Wallpaper Calculator
Calculate how many rolls of wallpaper you need. Accounts for pattern repeat, doors, windows, and different roll sizes. Never over-buy or under-buy again.
Room Dimensions
Openings
Standard: 2m height
Standard: 1.5m height
Roll Size
Pattern & Pricing
Results
Room Perimeter
9.92 m
Wall Height (with trim)
2.50 m
Roll Size
Standard UK (10.05m × 0.53m)
Drops Per Roll
5
Roll Calculation
Total Cost
£48.00
4 rolls × £12.00
Working Out Roll Counts Without Over-Buying
A standard UK wallpaper roll measures 10.05m long by 53cm wide, giving four to five drops per roll on a typical 2.4m ceiling height. The calculator takes your room perimeter, height, and the number of doors and windows, then deducts roughly 2m of full-height coverage per door and 1.5m per window. For a typical 12m perimeter room with one door and two windows at 2.4m height, that is around four rolls of plain paper.
Pattern repeat dramatically changes the answer. A plain paper has zero waste between drops - you cut where you cut. A 50cm pattern repeat means each new drop has to start where the pattern aligns, wasting up to 50cm at the bottom of every drop. A 64cm repeat (the largest typical) on the same room can push roll requirements from four up to six. The calculator factors this in and shows the wastage percentage so you understand where the extra rolls go.
Pattern Repeat, Trim Allowance and Why You Buy One Extra
Real-world hanging wastes more material than the maths suggests because of trim cuts at top and bottom (10cm allowance is standard), pattern alignment errors during hanging, and offcuts above doors and windows that can't be reused. Always order one extra roll beyond what the calculator returns. It costs £10 to £30 extra at typical UK roll prices but saves a frantic dye-lot match if you run short halfway through.
Dye lots are the other gotcha. Wallpaper printed in different production runs can vary subtly in shade, and matching mid-job is nearly impossible. Buy all your rolls together, check the batch number is identical on each, and store the spare unrolled (a partly used roll re-rolled tends to crease). For room measurement help see the [Paint Calculator](/paint-calculator), which works out paint volumes for any leftover walls or ceilings.
Rolls Required by Room Size (2.4m ceiling, plain paper)
| Room Perimeter | Doors | Windows | Standard Rolls |
|---|---|---|---|
| 8m (small bedroom) | 1 | 1 | 3 |
| 12m (double bedroom) | 1 | 2 | 4 |
| 16m (lounge) | 1 | 2 | 5 |
| 20m (large lounge) | 2 | 3 | 6 |
| 24m (open-plan) | 2 | 4 | 8 |
Frequently Asked Questions
How many rolls do I need for a small bedroom?
A typical small UK bedroom of 3m by 4m at 2.4m ceiling height has a 14m perimeter. Deducting one door and one window leaves around 11m of net coverage. With plain paper that is three rolls; with a 50cm pattern repeat, four rolls. Always add one extra for trim and a dye-lot safety margin.
Can I wallpaper over existing wallpaper?
Generally no. The new paste reactivates the old paste and can lift both layers, leaving bubbles and seams. Strip the old paper first using a steam stripper or wallpaper remover gel. The exception is lining paper underneath, which is designed to take a new finish layer. Walls should be smooth, dry and primed before hanging anything textured.
What about the area above the door?
The calculator deducts a full door-height of 2m from your perimeter, which slightly underestimates roll needs because the area above the door (40 to 60cm) still needs covering. In practice the offcuts from the door area can usually cover that gap, but if you want to be conservative reduce the deducted door count by half.
Do wide rolls (1.06m) save money?
Sometimes. Wide UK rolls are 10.05m long by 1.06m wide, double the area of a standard roll, and typically cost around 80% more rather than double - so per square metre they're cheaper. The catch is fewer drops per roll mean less flexibility around tricky cuts, and pattern matching on wider strips is harder for amateurs. Beginners usually do better with standard width.
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