15 × 12 ft room, 10% wastage, 20 sq ft boxes
198 sq ft to cover, 10 boxes, about $700 at $3.50 per sq ft.
Flooring calculator
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The room is a rectangle. The wastage allowance covers cuts and offcuts: 5% for a simple room, 10% usual, 15% for diagonal layouts or many corners. Boxes are rounded up.
ft
ft
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sq ft
Boxes to buy
10
180 sq ft of floor plus 10% wastage is 198.0 sq ft. 10 boxes cover 200 sq ft. About $700 at $3.50 per sq ft.
- Floor area
- 180 sq ft
- Area in m²
- 16.7
- With wastage
- 198.0 sq ft
- Material cost
- $700
Boxes at other wastage allowances
| Wastage | Sq ft to buy | Boxes | Cost |
|---|---|---|---|
| 5% | 189.0 | 10 | $700 |
| 10% | 198.0 | 10 | $700 |
| 15% | 207.0 | 11 | $770 |
Buying flooring without a second trip
Flooring is sold by the box, and each box covers a set number of square feet. To know how many to buy, work out the floor area, add an allowance for the pieces you cut away, and divide by the box coverage.
A 15 × 12 ft room is 180 sq ft. With 10% for cuts, that is 198 sq ft. If a box covers 20 sq ft, you need 9.9 boxes, so you buy 10. At $3.50 a square foot, the material costs about $700. The table shows the same room at 5%, 10% and 15% wastage.
Wastage depends on the room and the layout. A straight run in a rectangular room wastes little. Every doorway, closet and corner adds cuts. Planks laid on a diagonal waste the most, because every row ends in an angled cut.
Check the batch or lot number on every box. Colours vary a little between production runs, and mixing them can show in daylight.
Sources
What this calculator does not account for
- Rectangular rooms only; split L-shapes into parts.
- Underlayment and trim are not included.
How this is calculated
Formula: Boxes of flooring
boxes =round up(length × width × (1 + wastage) ÷ box coverage)What the symbols mean
- length × widthFloor area in square feet.
- wastageExtra for cuts: 5% to 15%.
- box coverageSquare feet in one box, printed on the box.
Good to know
- For tiles in mm sizes, use the tile calculator.
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Worked examples
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<iframe src="/embed/flooring-calculator" title="Flooring calculator" width="100%" height="720" style="border:0;max-width:42rem" loading="lazy"></iframe>Questions
How much extra flooring should I buy?
About 10% for a normal room. Use 5% for a plain rectangle and 15% for diagonal layouts or rooms with many corners.
How many boxes of flooring for 180 sq ft?
With 10% wastage and 20 sq ft boxes, 10 boxes.
How do I measure an L-shaped room?
Split it into two rectangles, work out each, and add the areas.
Should I keep spare boxes?
Yes. One spare box from the same batch makes later repairs much easier to match.
Is underlayment included?
No. Buy underlayment for the floor area without wastage, plus a little overlap.