Tile Calculator

What is the tile calculator?

The tile calculator tells you how many tiles and boxes to buy for a floor, wall or splashback. It takes the area you want to cover, the size of the tile, the width of the grout joint and an allowance for waste, then rounds up to whole tiles and whole boxes. Add the price per box and it estimates the cost too.

How to calculate tiles

1. Choose metric (metres and millimetres) or imperial (feet and inches).
2. Enter the length and width of the area. Use Subtract area for fixed items such as a kitchen island or shower tray.
3. Enter the tile length, width and grout gap.
4. Set the waste percentage and how many tiles come in a box. Add a price per box if you want a cost.
5. Read the tiles and boxes needed, then copy the breakdown for your shopping list.

How the numbers are worked out

• Tile area with grout: (tile length + gap) x (tile width + gap). Including the joint gives a slightly lower and more realistic count.
• Tiles: area divided by tile area, plus the waste percentage, rounded up.
• Boxes: tiles divided by tiles per box, rounded up, with the area the boxes cover.
• Grid check: the number of rows and columns needed to cover a rectangle, counting cut pieces as whole tiles, for comparison.

Choosing a waste allowance

Every tiling job cuts tiles at the edges, around pipes and in doorways, and some tiles break. Ten percent extra is common for a straight layout in a simple room. Diagonal, herringbone and other patterned layouts create more offcuts, so allow fifteen percent or more. Large format tiles and rooms with many corners also need a bigger allowance. A few spare tiles are worth keeping for future repairs, because the same shade can be hard to find later.

Tips for tiling projects

Check that all boxes come from the same batch or lot number, as shades vary between production runs. Lay out tiles dry before fixing to plan where the cuts will fall and to avoid thin slivers at the edges. For walls, measure each wall separately and add the areas. If you are using a pattern with two tile sizes, calculate each tile separately for the area it covers.

Example

A kitchen floor of 4 x 3 m is 12 square metres. With 600 x 600 mm tiles and a 3 mm joint, each tile covers about 0.364 square metres, so the floor needs about 33 tiles before waste. Adding ten percent gives 37 tiles. At four tiles per box that is 10 boxes, which leaves three spare tiles for future repairs.