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CALCPARK

Tile Calculator

Work out how many tiles and boxes you need from the room size, tile size, grout gap and waste allowance, in metric or imperial, with the cost if you know the price.

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How to use it

  1. Enter the surface as length × width (m, cm, ft or in) or as a total area in m² or ft². For L-shaped rooms, add the areas of the rectangles.
  2. Enter the tile size as printed on the box (e.g. 30 × 60 cm or 12 × 24 in) and the planned grout gap.
  3. Keep the 10% waste allowance or raise it for diagonal layouts, mosaics and rooms with many obstacles.
  4. Optionally enter the tiles per box and the price per box or per tile to see the number of boxes, the spares and the cost.
  5. Copy the summary or share the link with your tiler or the shop.

Example

Floor 4 × 3 m = 12 m², tiles 30 × 30 cm, 3 mm joint, 10% waste, 10 tiles per box at 25.00 a box. Each tile with its joint covers 0.303 × 0.303 = 0.091809 m²; 12 ÷ 0.091809 = 130.7, so 131 tiles cover the floor. With 10% waste: 131 × 1.1 = 144.1 → 145 tiles; 145 ÷ 10 = 14.5 → 15 boxes, 5 spare tiles, cost 375.00.

Formula and assumptions

cell = (tile length + joint) × (tile width + joint)
tiles = ⌈ area ÷ cell ⌉
with waste = ⌈ tiles × (1 + waste % ÷ 100) ⌉
boxes = ⌈ with waste ÷ tiles per box ⌉;   spare = boxes × per box − with waste
grout share = 1 − (tile length × tile width) ÷ cell

The area method assumes cut-offs can be reused at the opposite edge, which is true for straight layouts in rectangular rooms; the waste allowance covers the pieces that cannot be reused, breakages and future repairs. Half a joint sits on each side of a tile, so one full joint width per tile per direction is the right average. The calculator does not subtract door openings, fixtures or skirting, and does not estimate adhesive or grout quantities – those depend on the trowel notch and joint depth.

Sources: Tile Council of North America – Handbook for ceramic, glass and stone tile installation, The Tile Association (UK) – Technical guidance.

Questions

How many 60 × 60 cm tiles per square metre?
With a 3 mm joint each tile covers 0.603 × 0.603 = 0.3636 m², so 2.75 tiles per m² – 3 when rounded up for a single square metre, and 28 for 10 m² before waste.
Why does the result not change when I add a door opening?
The tool works from the surface you enter. Subtract openings yourself if they are large; for a standard door threshold the difference is one or two tiles and is covered by the waste allowance.
How much waste for a diagonal or herringbone pattern?
Plan 15–20%. Every edge tile is cut at an angle and the off-cut rarely fits elsewhere, so the loss is roughly double that of a straight layout.