Wallpaper Calculator — Free & Easy
Calculate wallpaper rolls based on total wall width, wall height, roll size, vertical pattern repeat, trimming length and an extra waste allowance.
Loading the interactive calculator. Enable JavaScript to enter your values, or use the formulas and worked example below.
How to use the Wallpaper Calculator
Calculate wallpaper rolls based on total wall width, wall height, roll size, vertical pattern repeat, trimming length and an extra waste allowance.
- Step 1. Add the widths of all wall sections that will be papered.
- Step 2. Enter the full wall height and extra trimming required per drop.
- Step 3. Use the exact dimensions and vertical repeat printed on the wallpaper label.
- Step 4. Plan rolls from full hanging drops rather than simply subtracting window area.
Important: Straight-match full-drop estimate; check offsets, batch numbers and manufacturer hanging directions.
Wallpaper Calculator formula explained
Full drops = ceil(wall width ÷ roll width). Adjusted drop length = ceil((wall height + trim) ÷ pattern repeat) × pattern repeat, or height + trim with no repeat. Drops per roll = floor(roll length ÷ cut length).
All calculator outputs depend on the measurements, units and assumptions you enter. Intermediate calculations use unrounded numeric values; formatted results may be rounded for easier reading. For any consequential purchasing or construction decision, verify supplier specifications and regulations.
Worked example with real numbers
A 36 ft total wall width with 1.75 ft-wide wallpaper needs 21 drops. If each drop uses 8.5 ft and the roll is 33 ft long, each roll yields 3 drops. Seven rolls are the base; 10% extra rounds the purchase to 8.
The example illustrates the formula independently of the interactive fields. You can change the values above to match your own project and compare results.
Frequently asked questions
Why not subtract windows from wall area?
Most wallpaper must be hung as full-height drops that are later trimmed around openings, so the width-based drop method is often more useful.
Does a pattern repeat increase roll usage?
Yes. Each drop may need to be cut to the next repeat interval, leaving less usable length per roll.
What is a half-drop match?
Adjacent drops are offset relative to each other. It requires additional matching logic and may need more material than this straight-match estimator.
Can I enter meters or centimeters?
Yes, provided all wallpaper and wall measurements use the same selected unit.