Flooring calculator

Flooring is sold by the box, not by the room, so the useful answer is never “13.4 square metres” — it is “seven boxes”. Enter the room size below and you will get the area, the area once waste is allowed for, and how many boxes that comes to for the common floor types.

Why the waste allowance matters

Every plank or tile that meets a wall gets cut, and the offcut is usually too short to start the next row. Ten per cent is the standard allowance for a straightforward rectangular room laid square to the walls. Push it to fifteen per cent if the room is L-shaped, if you are laying diagonally or in a herringbone pattern, or if the boards are long — long boards waste more at each end.

Buy the whole job in one order. Flooring is made in batches and the shade can shift noticeably between them, so a box bought three weeks later to finish a corner may not match. Keeping a spare plank or two after the job is worth it as well: a damaged board is much easier to replace from stock than from a discontinued range.

Box sizes vary a lot

The figures in the table are typical, not universal. Laminate boxes are commonly around 2.2 m², engineered wood nearer 1.8 m², and tile boxes vary with tile size more than anything else. The coverage is always printed on the pack — check it and adjust the waste figure above to match what you are actually buying.

Don’t forget the bits that are not flooring

  • Underlay, usually sold in rolls covering 10–15 m².
  • Beading or scotia to cover the expansion gap at the edges.
  • Threshold strips wherever the floor meets a different surface.
  • Adhesive or clips, depending on the system.

Beading follows the room’s perimeter rather than its area — the square footage calculator gives you that number too.

Rooms that are not rectangles

The calculator above assumes a rectangle. For an L-shaped room, work out each rectangle separately and add the box counts — or draw the room wall by wall and read the area straight off the plan, which is safer once there are alcoves and a chimney breast involved.

Common questions

How much flooring do I need for a 12x12 room?
A 12 ft by 12 ft room is 144 sq ft (13.38 m²). With a 10% waste allowance you need about 14.7 m², which is seven boxes of a typical 2.2 m² laminate.
How much extra flooring should I buy?
10% for a rectangular room laid square to the walls, and 15% for L-shaped rooms, diagonal layouts, herringbone patterns, or very long boards.
Do I measure under kitchen units and fitted wardrobes?
Usually not — flooring generally stops at fitted units that sit on the subfloor. Do include the area under freestanding appliances and anything you might later pull out, so you are not left with a bare patch.
Can I buy fewer boxes and top up later?
It is risky. Batches differ in shade and ranges get discontinued, so a top-up box may not match. Order the whole job at once and keep the spare.

Also useful: paint calculator and how to measure a room properly.