The method

How this calculator works

Measure the floor you will cover

Measure the length and width of the room wall to wall, at the widest points. The area is length × width, in square metres. The part of the floor that will end up under skirting boards and door frames is included, because the flooring runs underneath.

If the room is not a simple rectangle, split it into rectangles, measure each and add the areas. In a doorway, measure to the middle of the door opening, where the floor usually changes.

Add a waste allowance, then buy whole packs

Boards and planks must be cut at the end of each row, and some offcuts are too short to reuse. A commonly used allowance is 5–10% for a straight lay in a simple room, and 10–15% for diagonal or herringbone layouts or rooms with many awkward corners.

The calculator multiplies the area by 1 plus your allowance, divides by the coverage per pack and rounds up to a whole pack. Whatever is left over is worth keeping for repairs, because a matching batch may be hard to find later.

Check the gap, the underlay and the batch

Floating floors such as laminate usually need a small expansion gap around the edge of the room, commonly around 10 mm, which is hidden under skirting boards or trims. Follow the manufacturer's instructions for your product, because they decide the gap and the maximum run.

Buy underlay to match the floor area, not the number of packs. Try to buy all packs from the same batch, since shade can vary slightly between batches.

Worked example

Example: a 4 m × 3 m room, packs of 2.2 m²

  1. The floor area is 4 × 3 = 12 m².
  2. Add 10% for waste: 12 × 1.1 = 13.2 m².
  3. Divide by the pack coverage: 13.2 ÷ 2.2 = 6 packs exactly.

Practical answer: Buy 6 packs. They cover 13.2 m², so about 1.2 m² is left over for repairs. If your waste allowance were any higher, you would need a seventh pack.

Before you buy

Common measuring mistakes

  • Buying exactly the floor area with no allowance for cuts and offcuts.
  • Using the wrong coverage figure, for example the size of one board instead of the whole pack.
  • Measuring to the inside of the skirting boards instead of wall to wall.
  • Forgetting cupboards, alcoves, bay windows or hallways that will be floored as well.
  • Mixing packs from different batches, which can leave a visible shade difference.