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Tile Quantity Calculator

Work out how many floor tiles and boxes you need, including grout joints and a waste margin.

  • tile
  • tiles
  • flooring
  • grout
  • waste
  • boxes
  • square metres
  • square feet

About Tile Quantity Calculator

Running out of tiles partway through a job is a genuine headache: dye lots vary between batches, so the box you buy next week may not match the ones already on the floor. The fix is to work out the real quantity up front — including the grout joints that quietly change how many tiles fit, and a sensible waste margin for the offcuts every layout produces — then buy it all in one go.

This calculator turns your room size and tile size into the number of tiles to order, and, if you tell it how many tiles come in a box, the number of boxes. It accounts for the grout joint between tiles, lets you deduct doorways, and includes a waste slider with quick presets for straight, diagonal, and herringbone layouts, since the pattern you choose has a big effect on how much you'll cut and discard.

How to use

Enter the room's length and width, then the size of a single tile and your grout joint width. The floor area, tile count, and box count update as you type, in both square metres and square feet. Switch between metric and imperial at the top.

Set the waste margin with the slider, or tap a layout preset: 10% for a standard straight lay, 15% for diagonal, 20% for herringbone or rooms with lots of cuts around fixtures. If you know how many tiles are in a box, enter it to get a box count — always round boxes up and buy from a single batch so the shade is consistent. The doorway field trims a small threshold area per door from the total.

Frequently asked questions

  • How many tiles do I need per square metre?

    Divide one square metre by the area a single tile covers, including its grout joint. A 600 × 600 mm tile with a 3 mm joint occupies about 0.363 m², so you need roughly 2.8 tiles per square metre; a 300 × 300 mm tile needs about 11. The calculator does this for your exact tile size and then adds your waste margin, so you can read the order quantity straight off.

  • How much waste should I allow for tiles?

    A 10% margin is the usual recommendation for a standard straight layout, covering offcuts, the occasional breakage, and a few spares for future repairs. Increase it to about 15% for diagonal layouts and 20% for herringbone or rooms with lots of cuts around cabinets, pipes, and alcoves — angled cuts waste more of each tile. The waste slider and presets handle this for you.

  • Does the grout joint change how many tiles I need?

    Yes, slightly. Each tile effectively occupies its own size plus one grout joint of spacing, so wider joints mean each tile covers a little more floor and you need marginally fewer. The effect is small for thin joints but real — this calculator includes the joint width in its coverage figure rather than ignoring it like simpler tools do.

  • Why should I buy all my tiles at once?

    Tiles are produced in batches, and the colour or shade can vary subtly between batches — what manufacturers call the dye lot or shade code. If you run short and buy more later, the new tiles may not match the ones already laid, and the difference is most visible across a large floor. Order your full quantity, including the waste margin, from a single batch.

  • Why does the calculator subtract area for doors?

    A doorway is a gap where the floor passes into the next room, so the threshold strip under the door is generally not part of the tiled field. The deduction is a standard, modest figure (about 0.09 m² per door) — for floor tiling it is a minor adjustment, unlike wall tiling where door and window openings remove a lot of area. Leave it at zero if you intend to tile right through the openings.

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