Wallpaper Calculator — Free Online Tool
Wallpaper's pattern repeat can quietly double your waste — a big motif means every strip loses inches to matching. This wallpaper calculator converts your wall area into rolls, with a 15% allowance for pattern matching and trimming.
What is the Wallpaper Calculator?
A standard US double roll covers about 56 square feet in theory, but pattern repeat eats into that fast: a 24-inch repeat can waste nearly two feet per strip. Measure every wall's width and height, multiply, and subtract only large openings like doors and windows — small trim areas aren't worth deducting.
Always buy all rolls from the same batch number — wallpaper dye lots are notoriously visible. The 15% allowance in this wallpaper calculator covers pattern matching on typical repeats; for very large repeats (over 24 inches) or diagonal patterns, add another roll. Keep one full roll spare: patching a damaged section years later from a different batch will show.
How to use this calculator
- Measure each wall's width × height and total the area.
- Subtract large doors and windows only.
- Check the roll coverage on your wallpaper (double rolls ≈ 56 sq ft).
- Click Calculate Rolls and verify all rolls share one batch number.
Formula
Frequently asked questions
What is pattern repeat?
The vertical distance before the pattern repeats. Bigger repeats waste more paper per strip — the main reason this wallpaper calculator adds 15%.
What is the difference between single and double rolls?
US wallpaper is usually sold as double rolls covering ~56 sq ft; European rolls are often smaller (~25 sq ft). Check your product.
Should I subtract windows and doors?
Only large ones. Small trim and outlets aren't worth the math — the waste allowance covers them.
Does peel-and-stick use the same math?
Yes — area is area. The same roll-count logic applies to peel-and-stick wallpaper.