About this calculator
Rolls of wallpaper by counting strips, the way decorators do. This is more accurate than dividing area by area, because offcuts from each roll are wasted.
How it’s calculated
Drop = wall height + pattern repeat + 4" trim. Strips per roll = floor(roll length ÷ drop). Strips = perimeter (less some allowance for doors and windows) ÷ roll width. Rolls = strips ÷ strips per roll, plus one spare.
Worked example
With these inputs:
- Room length
- 14 ft
- Room width
- 12 ft
- Wall height
- 8 ft
- Doors
- 1
- Windows
- 2
- Roll width
- 20.5 in
- Roll length
- 33 ft
- Pattern repeat
- 0 in
the result is:
- Rolls needed
- 11 rolls
- Strips needed
- 28
- Full strips per roll
- 3
- Drop length (incl. trim + repeat)
- 8' 4"
Tips from the trade
- Check that every roll has the same batch number.
- Large drop-match patterns waste more. Some designs need an extra roll per room.
Results are estimates for planning and pricing. Check quantities against your drawings, the manufacturer’s data and local building codes before ordering.