Each wallpaper drop includes top and bottom trim and is rounded up to a whole pattern repeat. Full drops per roll are then calculated without joining fragments. This implements a straight-match approximation. Half-drop pattern matching and automatic opening deductions are not implemented; do not reduce the count for a window without checking usable drops.
Worked reference example
Illustrative inputs in metres and SI units; the price is an example entered by the user, not a market quotation. Numeric reference verified by the automated test suite.
- Width
- 3
- Wall height
- 2.5
- Roll width
- 0.53
- Roll length
- 10
- Pattern repeat
- 0.32
- Trim at each end
- 0.05
- Allowance
- 10
- Price per purchase unit
- 2
- Result
- 3
- Cost (example currency units)
- 6
Calculation method
Lᵦ = ceil((H + 2t)/R) × R; nᵣ = floor(Lᵣ/Lᵦ); N = ceil(ceil(W/wᵣ × (1+r/100))/nᵣ)Measure. Calculate. Build.
- Use actual dimensions and split complex rooms into rectangles.
- Allow for cuts, joints and package sizes. Compare stock formats.
- Combine your results in a shopping list you can save and print.
Sources & limits
Planning estimates; verify measurements and product data before purchasing.
Prices are supplied by you. Area estimates do not establish a feasible cutting arrangement. These tools do not assess structural loads or issue construction approvals.