Wallpaper Calculator
Wallpaper cannot be estimated reliably by area alone. This calculator models full-height drops, rounds each drop length up to the pattern repeat, and then rounds rolls up.
How to use this calculator
Enter the total wall width and finished height.
Enter roll dimensions, trim allowance, and pattern repeat from the label.
Review usable drops per roll and the rounded-up roll count.
Formula
Drops = ceil(total wall width ÷ roll width). Adjusted drop = ceil((wall height + trim) ÷ repeat) × repeat. Rolls = ceil(drops ÷ floor(roll length ÷ adjusted drop)).
Worked example
For 10 drops at 2.5 m adjusted length from a 10 m roll, each roll yields 4 drops, so ceil(10 ÷ 4) = 3 rolls.
Assumptions and limits
- Every required piece is a full-height vertical drop.
- Pattern repeat is treated as a straight repeat.
- Doors, windows, matching offsets, defects, and product-specific instructions may change the order.
Sources
Related calculators
Frequently asked questions
Why does the wallpaper result differ from wall area divided by roll area?
Full drops leave unusable offcuts, and pattern alignment can increase each drop length, so area-only division often understates rolls.
Can I use metric and US customary units in the Wallpaper Calculator?
Yes. Unit changes convert the same canonical measurement; they do not reinterpret or round your original value.
When does the calculator round?
The calculation keeps full precision internally and rounds only the displayed result. Whole packages are rounded up at the final step.
Last updated · formula-v1 · content-2026-08-14 · Trusty Calculator Editorial Team