For an irregular room, enter separate non-overlapping rectangular segments. Their areas replace the main room dimensions. Subtract excluded areas once, then apply allowance. Use the manufacturer's stated coverage per pack; the result rounds up to complete packs. Layout-specific cutting efficiency is not calculated.
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.
- Length
- 4
- Width
- 3
- Area deductions (trim tool: length)
- 0
- Coverage per pack (paint: m²/L)
- 2.2
- Allowance
- 10
- Price per purchase unit
- 2
- Result
- 6
- Cost (example currency units)
- 12
Calculation method
N = ceil(A × (1 + r / 100) / Aₚ)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.