Tile Calculator
Find out how many tiles to buy for a floor or wall. Include the grout gap and an allowance for cuts, and see the number of boxes and the cost.
A kitchen floor 4 m by 3 m, tiled with 300 mm square tiles and a 3 mm grout gap in straight rows:
- Area = 4 × 3 = 12 m²
- Each tile plus its gap takes 303 mm × 303 mm, which is 0.0918 m²
- 12 ÷ 0.0918 = 130.7, so 131 tiles cover the floor
- Add 10% for cuts and breakages: 131 × 1.1 = 144.1, so buy 145 tiles
If the tiles come in boxes of 11, that is 14 boxes (154 tiles). After laying 131 tiles, that leaves 23 spare for cuts, breakages and future repairs.
- Buy all your tiles at once and check the batch numbers match, as colour can vary between batches.
- Large format tiles and diagonal layouts create more offcuts, so allow extra.
- Keep a spare box for repairs, as designs are often discontinued.
- Measure twice, and measure each wall or alcove separately if the room isn't a simple rectangle.
How many tiles do I need for a room?
Measure the length and width of the area in the same units, multiply them to get the area, then divide by the area of one tile (including the grout gap). Then add extra for cuts and breakages. This calculator does all three steps and rounds up to whole tiles and whole boxes.
How much extra should I allow for wastage?
Around 10% is normal for tiles laid in straight rows in a simple room. Allow 15% for diagonal layouts and 15 to 20% for herringbone, large format tiles or a room with lots of corners and alcoves. Natural stone with variation in colour may also need a little more, so you can pick the best pieces.
Should I include the grout gap in my calculation?
Yes, for a precise count. Each tile takes up its own size plus half the gap on every side. The difference is small with a 2 to 3 mm joint but grows with mosaic tiles, small tiles or wide joints, where the gaps make up a large share of the surface.
Should I buy all my tiles in one go?
Yes. Tiles are made in batches and the colour and size can vary slightly between them, which shows once they are laid. Buy everything at once, and check the batch number on each box matches. It is also worth keeping a box or two spare for future repairs, as the design may be discontinued.
How do I measure for wall tiles?
Measure the height and width of each wall you are tiling and multiply to get its area. Add the walls together, then subtract the size of any windows, doors or built-in fittings. You can enter the total wall area as the length and width of one big rectangle, and use the deduction box for the openings.
How do I convert tile boxes into square metres?
Tile boxes usually state the coverage in square metres (or square feet), and the number of tiles inside. If you enter the tiles per box, the calculator rounds your total up to complete boxes and shows the area they will cover. Boxes are only sold whole, so you will often end up with a few tiles spare.