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Flooring Calculator

Work out how much flooring and how many boxes to buy.

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How to use

  1. 1.Pick your units, then enter the room length and width to get the floor area.
  2. 2.Set the waste allowance — 5–10% suits a straight layout, 15–20% covers diagonal, herringbone or parquet patterns and large tiles.
  3. 3.Enter the coverage per box to see how many boxes to buy, rounded up to whole boxes, alongside the area and total with waste.

About Flooring Calculator

To work out how much flooring you need, multiply the room length by the width to get the floor area, add a waste allowance for offcuts and pattern matching, then divide by the coverage listed on the box and round up to whole boxes. This calculator does all three steps live as you type, in either feet or metres.

The first number is the room area: length × width. A room that is 12 ft by 10 ft is 120 square feet; a 4 m by 3 m room is 12 square metres. Keep both measurements in the same unit and the answer comes out in that unit squared. For an L-shaped or awkward room, split it into rectangles, work out each area, and add them together.

The second number is the waste allowance. You never lay a floor with zero offcuts — planks and tiles get trimmed at the walls, around doorways and against pipes, and a few pieces crack or come damaged. For a standard straight or brick-bond layout, adding 5 to 10 percent is the usual advice, and 10 percent is a safe default. For a diagonal, herringbone or parquet layout, or with large-format and heavily patterned tiles, the offcuts are bigger, so add about 15 to 20 percent instead. The calculator applies your chosen percentage to the room area: area with waste = area × (1 + waste ÷ 100). A 120 sq ft room at 10 percent becomes 132 sq ft to buy.

The third number is how many boxes to buy. Flooring is sold by the box, and each box states how much area it covers — for example 20 sq ft or 2 square metres. Divide the area-with-waste by the coverage per box and round up, because you cannot buy a fraction of a box: 132 ÷ 20 = 6.6, which rounds up to 7 boxes. Rounding up is the whole point; buying exactly 6.6 boxes' worth would leave you short mid-job, and dye lots vary between deliveries so a top-up box rarely matches. Many installers keep one extra box as spares for future repairs.

A few things this calculator keeps simple. It assumes rectangular rooms, so add rooms together yourself for a whole home. It uses one waste percentage, so raise it for complex patterns or a room full of tricky cut-outs. And box coverage is optional — leave it blank to see just the area and the amount to buy, then fill it in once you know the product.

Everything here is an estimate to help you order with confidence, not a cutting plan. Measure each room twice, check the exact coverage printed on the box you are buying, and keep the calculation to hand at the store. All calculations run entirely in your browser.

Frequently asked questions

How much flooring do I need?
Multiply the room length by the width for the floor area, add a waste allowance of about 10%, then divide by the area each box covers and round up. For example, a 12 ft by 10 ft room is 120 sq ft; with 10% waste that is 132 sq ft, and at 20 sq ft per box you buy 7 boxes.
How much extra flooring should I buy for waste?
Adding 5 to 10 percent to the room area is the usual advice for a standard straight or brick-bond layout, and 10 percent is a safe default. This covers offcuts at the walls and doorways, plus the odd cracked or damaged piece. Keeping one extra box as spares for future repairs is also sensible.
How do I work out the number of boxes?
Take the area including waste and divide it by the coverage printed on the box, then round up to the next whole box because you cannot buy part of a box. If the area with waste is 132 sq ft and each box covers 20 sq ft, that is 132 ÷ 20 = 6.6, which rounds up to 7 boxes.
How much extra do I need for a diagonal or herringbone pattern?
Diagonal, herringbone and parquet layouts create more offcuts because planks are cut at an angle, so add about 15 to 20 percent waste rather than 10. Large-format or heavily patterned tiles that need aligning also waste more, so raise the percentage in the calculator to match.
Can I calculate in feet or metres, and for more than one room?
Yes. Switch the units selector to feet or metres and enter every measurement in that unit; the area is shown in that unit squared, with a rough conversion to the other. For several rooms, work out each rectangle separately and add the areas, then apply your waste allowance and box coverage to the total.

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