Tile calculator

What it works out

This works out how many tiles a floor or wall needs, and how many boxes to buy. It allows for the joints between tiles, anything inside the area you won't tile, and the extra cutting that some layouts need.

Once you have the tiles, the grout and adhesive calculator works out what holds them in place, with your figures carried across.

How it works

Add the areas to tile, by size or by area, and take off what won't be tiled, like a bath or a window. Each tile, with its joint, covers a little more than its own face, so the area is divided by the tile plus joint.

The waste allowance goes on top, and the layout adds more: offset and diagonal layouts cut more tiles at the edges, and herringbone more again. The number of tiles in a box comes from the area the box covers, and the tiles are rounded up to whole boxes.

A worked example

An area 3 m by 2 m, laid straight with tiles 30 cm by 60 cm and 3 mm joints, in boxes that cover 1.44 m².

1. Area 1: 3 m × 2 m = 6 m²
2. Tiles: 6 m² ÷ 0.18 m² (one 30 cm × 60 cm tile with its 3 mm joint) = 32.8
3. 32.8 + 10% for waste + 0% for the straight layout → 37 tiles
4. 1.44 m² a box ÷ 0.18 m² a tile = 8 tiles a box
5. 37 tiles ÷ 8 a box → 5 boxes of 1.44 m² (40 tiles)

Common mistakes

• Forgetting the cuts. Every edge, corner and pipe needs a cut tile, and cut pieces rarely fit anywhere else. Small rooms waste proportionally more.
• Ignoring the layout. Diagonal and herringbone layouts look great and cut far more tiles. Choose the layout before you order.
• Not keeping spares. A few spare tiles from the same batch make it easy to replace one that cracks years later, when that tile may no longer be made.
• Mixing batches. Tiles vary in shade and size between batches. Check the batch code on every box, and mix tiles from several boxes as you lay them.

Questions people ask