Free tool
Tile calculator
Area and tile size in, tiles and boxes out.
Tiles are priced by the square metre, sold by the box and laid one at a time, and the three numbers rarely line up neatly. This works out all of them, including the box count, which is what the merchant will actually ask you for.
The sum
Divide the area you are covering, plus an allowance, by the area of one tile. A 600 by 300 tile covers 0.18 of a square metre, so 12 square metres plus ten per cent is 13.2 square metres, which is about 74 tiles.
Boxes vary, but 1.44 square metres is a very common box for a 600 by 300. Check the label, because it changes with the tile size and it is the unit you are charged in.
The allowance is not padding
Ten per cent is the standard and it is the number to use for a straight lay in a room that is close to square. Go higher when any of these are true.
- A diagonal or herringbone lay. Every edge tile is cut, and the offcut from one is rarely usable on another. Fifteen to twenty per cent.
- A room that is out of square, which most older houses in Albury, Wodonga and Wagga are. The cut on one wall tapers, so those tiles are single use.
- Large format tiles. Fewer, bigger tiles mean each breakage costs more area.
- A patterned or directional tile, where you cannot rotate a piece to make it fit.
Buy the extra box, not the exact number
This is the one that catches people. Tiles are made in batches and the colour shifts slightly between them, which the industry calls a dye lot or shade batch and prints on the box. If you run out and go back in a fortnight, the new box will usually be a different batch and it will show, especially on a plain colour under side light.
Keep the leftovers and a few whole tiles from the same batch. A cracked tile in three years is a twenty minute repair if you have a match, and a re-tiled floor if you do not.
What else you will need
Adhesive and grout are quoted by coverage on the bag and depend on the notch of the trowel, the tile size and how flat the substrate is. Add waterproofing for a wet area, and trims for external corners and edges. None of that is in the count above.
Common questions
How many tiles do I need per square metre?
Divide one by the area of the tile in metres. A 600 by 300 tile is 0.18 of a square metre, so about 5.6 tiles to the square metre. A 300 by 300 is 0.09, so about 11.2. The calculator above does it from the tile dimensions in millimetres.
How much wastage should I allow for tiling?
Ten per cent for a straight lay in a square room. Fifteen to twenty for a diagonal or herringbone pattern, for large format tiles, or for an older house where the walls are not square, because those cuts taper and the offcuts cannot be reused.
Why does buying an extra box matter?
Tiles are made in batches and the shade shifts slightly between them. The batch number is printed on the box. If you run short and buy more later it will usually be a different batch, and on a plain colour under side light the difference is visible. Buying the extra box up front is much cheaper than matching one later.
Does the calculator include adhesive and grout?
No. Adhesive and grout coverage depends on the trowel notch, the tile size and how flat the floor is, and it is printed on the bag. The calculator covers tiles and boxes only, so add adhesive, grout, waterproofing and trims separately.