What this tool does
Calculate the four walls of a rectangular room, subtract doors and windows, then add a cutting allowance before estimating whole rolls.
How to use it
- Measure room length, room width and wall height in metres.
- Enter the total area of openings, waste rate and the dimensions of one roll.
- Review gross wall area, adjusted required area and the estimated roll count.
Formula and method
Gross wall area = 2 × (room length + room width) × wall height. Subtract openings, add the waste percentage, then divide by roll width × roll length and round up.
Example
A 4×3m room with 2.4m walls has 33.6m² of wall. After subtracting 4m² and adding 10%, the required area is 32.56m²; 0.53×10m rolls give a simple estimate of 7 rolls.
Useful for
- Planning a DIY wallpaper project
- Comparing wall areas between rooms
- Preparing a materials estimate
Limits and notes
Pattern matching, strip lengths, columns, slopes and a product’s usable width can require more material than this area-only model. Follow the manufacturer’s repeat and installation guidance before buying.
Frequently asked questions
Does it include the ceiling?
No. It covers four rectangular walls. Calculate a ceiling separately as length × width.
Must I subtract every opening?
Small openings may be left as allowance, but subtracting large doors and windows usually improves the estimate.