Case 1
- Room length
- 5m
- Room width
- 4m
- Coverage per box
- 2m²
- Waste allowance
- 10%
11boxes
Open with these valuesFlooring Calculator
Change any value to update the result.
11boxes
Boxes needed: 11 boxesExamples
How the result moves
Waste allowance (%) → Boxes needed (boxes)Your current valid inputs, with one value varied across the range.
How the result moves
Held fixed: Room length 5.00 m, Room width 4.00 m, Coverage per box 2.00 m².
| Waste allowance (%) | Boxes needed (boxes) |
|---|---|
| 5 | 11 |
| 8 | 11 |
| 10Your value | 11 |
| 13 | 12 |
| 15 | 12 |
Length × width is the floor area; add the waste allowance, divide by what one box covers, round up. A 5 × 4 m room at 10 % waste with 2 m² boxes needs 11. Coverage per box is printed on the label and varies by plank size — 1.39, 1.99 and 2.54 m² are all real box sizes.
Worked examples
Case 2
- Room length
- 6m
- Room width
- 5m
- Coverage per box
- 2.5m²
- Waste allowance
- 10%
14boxes
Open with these valuesCase 3
- Room length
- 3m
- Room width
- 3m
- Coverage per box
- 1.5m²
- Waste allowance
- 0%
6boxes
Open with these valuesHow it's calculated
boxes = ⌈length × width × (1 + waste) ÷ coverage per box⌉
- StepMeasure length and width in metres; split an L-shaped room in two.Room length=5m·Room width=4m
- StepRead the coverage per box off the label — often near 2 m².Coverage per box=2m²
- StepSet the waste allowance: 10 % straight, 15 % diagonal or first time.Waste allowance=10%
- ResultThe count rounds up; a sealed box cannot be bought by the half.11boxes
What this number means
The waste allowance follows the pattern
10 % is the usual figure for a straight, plank-aligned layout, and the manufacturer behind this calculator multiplies the room area by 1.1. Go to 15 % for a first job, or for diagonal and herringbone patterns.
A sealed box cannot be split
The count rounds up because flooring is sold in whole boxes. Rounding at the end also leaves a small surplus for offcuts and later repairs.
Coverage per box is not always 2 m²
It is printed on the label and varies with plank size and brand. The source behind this calculator lists packs of 1.39, 1.99 and 2.54 m², so enter the figure for what you are actually buying.
Commonly misread
Misconception20 m² of floor means 20 m² of flooring.
CorrectionThe floor area is the start, not the order. A 5 × 4 m room at 10 % waste needs 22 m² of covering, which is 11 boxes of 2 m².
MisconceptionIf I run short I can pick up another box later.
CorrectionColour and finish vary slightly between production runs, so a later box may not match. Buy every box from the same batch in one purchase.
MisconceptionMy room is L-shaped, so I measured the longest length and width.
CorrectionThat bounding rectangle is larger than the actual floor. Split the room into two rectangles and add their areas instead.
Reference table
| Length, width, box coverage, waste | Floor area | Boxes |
|---|---|---|
| 3, 3, 1.5, 0 | 9 m² | 6 |
| 4, 3, 2, 10 | 12 m² | 7 |
| 5, 4, 2, 10 | 20 m² | 11 |
| 6, 5, 2.5, 10 | 30 m² | 14 |
| 8, 5, 2.5, 15 | 40 m² | 19 |
Questions
How much flooring do I need?
Multiply room length by width for the area, add the waste allowance, then divide by the coverage of one box and round up. A 5 × 4 m room is 20 m²; with 2 m² boxes at 10 % waste that is 22 ÷ 2, so 11 boxes.
How much waste should I add?
10 % is the usual allowance for a straight, plank-aligned layout, and the manufacturer behind this calculator says to multiply the room area by 1.1. Go to 15 % if you have not laid flooring before, or for diagonal and herringbone patterns.
Where do I find the coverage per box?
It is printed on the box label in square metres. It varies with plank size and brand — the source behind this calculator lists packs of 1.39, 1.99 and 2.54 m². Enter the figure for the product you are actually buying.
Why does the result round up to a whole box?
Flooring is sold in sealed boxes, so a fractional box has to be rounded up. Rounding the final figure up also leaves a small surplus for offcuts and later repairs.
Should I buy it all at once?
Yes. Colour and finish vary slightly between production runs, so buy every box from the same batch in one purchase. A later top-up may not match, which is another reason the waste allowance is worth keeping.