Tile Calculator

How many tiles do I need?

How it is calculated

The tool works in these steps. Tile area in m² is (w/100) × (h/100), because tile width and height are entered in centimetres. Base count is area / tile area, with the room area in m². Waste is added as × (1 + waste/100) to cover cuts, breakage and spares, and the total is rounded up to a whole tile. Boxes are ceil(tiles / tiles per box), since you can only buy full boxes. If waste is blank it is taken as 0, and all other fields must be above zero. Grout joints are not subtracted, so for wide joints the tile size should include them. Complex layouts or diagonal patterns need a higher waste figure.

Worked example

A floor of 20 m² with 30 × 60 cm tiles, 10% waste, 8 tiles per box. One tile covers 0.30 × 0.60 = 0.18 m². Base count: 20 / 0.18 = 111.1 tiles. Add 10%: 111.1 × 1.10 = 122.2, rounded up to 123 tiles. Boxes: 123 / 8 = 15.4, rounded up to 16 boxes (128 tiles, five spares).

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Common mistakes

  • Entering tile dimensions in millimetres or metres when the fields are in centimetres.
  • Entering the room area in square feet or cm² instead of m².
  • Skipping the waste allowance; cuts at walls and breakage usually need some extra tiles.
  • Rounding the boxes down, or ordering exactly the tile count without rounding to whole boxes.
  • Not accounting for pattern layouts (diagonal, herringbone) that waste more than a straight grid, or for the extra tiles worth keeping for future repairs.

About this calculator

This tool works out how many individual tiles and full boxes are needed to cover a given floor or wall area, based on the area to be tiled, the size of a single tile, and a waste allowance percentage that accounts for cuts, breakage and pattern matching around edges and corners. Without that waste margin, a project almost always runs short partway through, since straight edge cuts rarely use a whole tile.

It is used by homeowners and DIY renovators planning a bathroom, kitchen or floor tiling project before ordering materials, and by contractors putting together a materials estimate for a client. Because tiles are usually sold by the box rather than individually, rounding the raw tile count up to full boxes is what actually determines the purchase order and the total cost.

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Comments (1)

  • Editorial team

    Buy every box in one go. Tiles from different production batches can differ slightly in shade, and a later top-up may not match what is already on the wall. The tool counts boxes from tiles per box, so read that number off the packaging, where boxes are often labelled by square metres instead. Enter the net area, with doors and windows already subtracted. Is your project a floor, a wall, or a backsplash?

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