What this calculator does
A box count is more useful at the shop than an area alone. This tool calculates a rectangular floor, subtracts any area you exclude, adds your cutting allowance and rounds up to full boxes. Use the coverage printed on the exact product packaging.
Formula, assumptions and sources
Net area = length × width − excluded area. Required coverage = net area × (1 + waste / 100). Boxes = round up(required coverage ÷ coverage per box). Use the same area units for exclusions and box coverage. Price is per box. Layout, pattern and cuts determine a suitable waste percentage.
Worked example
This example uses the initial values shown in the form. It is illustrative and is not a saved personal result.
Example inputs
- Measurement system
- Metric
- Room length (m or ft)
- 5
- Room width (m or ft)
- 4
- Area to exclude (m² or ft²)
- 0
- Extra material allowance (%)
- 10
- Coverage per box (m² or ft²)
- 2.2
- Currency
- USD
- Price per purchase unit (optional)
- 0
Example result
These are alternative totals, not quantities to add together.
View chart data
| Item | Value |
|---|---|
| Net floor | 20 |
| With allowance | 22 |
| Whole-box coverage | 22 |
Material only; excludes delivery, labour and tax. A zero price means cost has not been entered. Treat separate rooms or products as separate scenarios; this does not optimise a tile layout.
Frequently asked questions
Can I calculate an L-shaped room?
Split it into non-overlapping rectangles and calculate their areas. For one combined purchase, use their total as length with width set to 1, keeping consistent units.
What waste percentage should I enter?
It depends on room shape, cuts, patterns and spare material requirements. The 10% default is an example, not a guarantee; confirm with your installer.
Method and example checked 4 November 2026. How we check calculations