Tile Calculator
See exactly how many tiles to buy for your floor — coverage and waste allowance included.
Always rounds up
You can only buy whole tiles, so the result is rounded up to the next whole tile — never short on the day.
Add a waste allowance
Cuts, breakages, and future repairs eat into your stack — 10% extra is the usual rule of thumb.
How many tiles do I need?
Floor area, tile size, and a little extra
The number of tiles you need comes down to three things: the area you are covering, the size of each tile, and how much spare you keep for cuts and breakages. Divide the floor area by the coverage of a single tile and you have the bare count; add a waste allowance and round up to whole tiles, and you have the number to buy. Enter your figures above to see both the tile count and the coverage of a single tile.
Enter your floor area, tile dimensions, and waste allowance to get the number of tiles to buy.
First work out the area one tile covers — length times width, converted from centimetres to metres. Divide the floor area by that figure, multiply by one plus the waste percentage, and round up.
Tiles = ⌈floor area ÷ tile area × (1 + waste%)⌉A 30 × 30 cm tile covers 0.30 m × 0.30 m = 0.09 m². Twenty square metres divided by 0.09 is about 222.2 tiles bare; multiply by 1.10 for the 10% waste allowance to get 244.4, then round up to 245 tiles.
Suppose you are tiling a 20 m² floor with 30 × 30 cm tiles and a 10% waste allowance.
Find one tile's coverage
0.30 m × 0.30 m = 0.09 m² per tile.
Divide the floor area
20 ÷ 0.09 = 222.2 tiles for the bare floor.
Add waste and round up
222.2 × 1.10 = 244.4, rounded up to 245 tiles to buy.
The figure is the number of whole tiles to buy, so always round up — a part tile still means purchasing a full one and cutting it. The standard 10% waste allowance covers ordinary cuts and the odd breakage on a straight, grid-aligned layout. Bump it up to 15–20% for diagonal layouts, herringbone, or other patterns, where each cut leaves a larger offcut, and for rooms with many corners and obstacles. Tiles are sold by the box, so divide your total by the tiles per box and round up to whole boxes — and keep a few spares from the same batch, since dye lots vary between production runs.
The arithmetic is exact, but a real floor adds a few wrinkles.
Grout lines and complex layouts
The calculator uses the bare tile dimensions and ignores grout lines, so it slightly overestimates the count — a small surplus that works in your favour. It also assumes a simple rectangular area; L-shaped rooms, alcoves, and heavily patterned layouts generate more offcuts, so measure each section separately and lean towards the higher end of the waste range.