Explanation
Flooring packs to buy
Flooring is usually purchased in complete packs. The room area plus a cutting allowance may not divide evenly by a pack’s coverage, so the purchase count rounds up.
Measure the room and read the pack
Enter the rectangular room dimensions in metres and the coverage printed on one pack. Choose your cutting allowance based on layout and manufacturer guidance; 5 to 10% is common for straight lay, more for diagonal or herringbone.
N = ⌈L × W × (1 + a/100) ÷ p⌉
| N | Whole packs to buy |
|---|---|
| L | Room length |
| W | Room width |
| p | Area per pack |
| a | Cutting allowance |
20 m² in 2 m² packs
| Room length | 5 |
|---|---|
| Room width | 4 |
| Area per pack | 2 |
| Cutting allowance | 10 |
| Result | 11 packs |
Room area 5 m × 4 m = 20 m². Add the 10% allowance and divide by 2 m² per pack, then round up to whole packs = 11 packs.
Rounding a fractional pack up
| Room length | 3 |
|---|---|
| Room width | 3 |
| Area per pack | 2 |
| Cutting allowance | 0 |
| Result | 5 packs |
Room area 3 m × 3 m = 9 m². Add the 0% allowance and divide by 2 m² per pack, then round up to whole packs = 5 packs.
A small room with cutting allowance
| Room length | 2 |
|---|---|
| Room width | 2 |
| Area per pack | 3 |
| Cutting allowance | 5 |
| Result | 2 packs |
Room area 2 m × 2 m = 4 m². Add the 5% allowance and divide by 3 m² per pack, then round up to whole packs = 2 packs.
Diagram of this result
Filled squares are packs you use in full; the part-filled square is the share of the last pack you need. The rest of it is spare.
The exact pack count before rounding and the whole packs to buy are stated as numbers under the grid.
Common mistakes
Do not round the room area before calculating packs. A diagonal pattern, irregular room or spare boards can require a different allowance.
Assumptions and limits
One rectangular room; dimensions and pack coverage positive and at most one million. Allowance 0–100%. Always returns a whole pack count. No product compatibility, expansion gap or subfloor engineering is inferred. Material estimates only; verify measurements, product guidance and site requirements before ordering.
Why can the surplus exceed the allowance?
The allowance is applied first. Rounding to a complete pack can add another partial pack of surplus because packs cannot be purchased as fractions.
Method and references
Rectangle area scaled by an explicit percentage allowance, divided by the coverage of one pack and rounded up once at the end. Pack coverage and cutting allowance must come from the chosen product; no standard pack size is assumed.