Tile Calculator
Work out how many floor tiles and boxes to buy, with a waste allowance, rounded up.
How it works
Enter the room size and the tile size, each in its own unit. The floor area is divided by one tile's area to give the tile count, the waste allowance is added to the exact count, and the result is rounded up. Add a tiles-per-box figure from the box label to get whole boxes.
floor area = room length × room width
tiles required = ceil(floor area ÷ tile area)
tiles with waste = ceil(floor area ÷ tile area × (1 + waste ÷ 100))
boxes = ceil(tiles with waste ÷ tiles per box)Example
A 4 m × 3 m room is 12 m². A 60 × 60 cm tile is 0.36 m², so the bare floor needs 12 ÷ 0.36 = 33.33, which is 34 tiles. With 10% waste, 33.33 × 1.10 = 36.67, which is 37 tiles. At 4 tiles per box, 37 ÷ 4 = 9.25, so buy 10 boxes. That is 40 tiles, and 6 are left over after laying 34.
Common mistakes
- Mixing units. A 60 cm tile typed as 60 in the room's metre field would be a 60 m tile. Check each unit selector.
- Ignoring grout joints. The tile size you enter is the size of the tile only. If joints are wide, add the joint width to each tile dimension.
- Buying exactly the floor area. Cuts around edges and breakage mean the tiles from the bare-floor count are rarely enough.
About this calculator
Enter the room's length and width, the tile's length and width, and the waste allowance. The calculator divides the floor area by the area of one tile, adds the waste allowance to that exact count, and rounds up to whole tiles. If you also enter how many tiles come in a box, it rounds up to whole boxes and shows how many tiles you will have left over.
The room and the tiles have their own unit selectors, because rooms are usually measured in metres or feet and tiles in centimetres or inches. Grout joints, cuts and layout pattern are not modelled. The waste allowance is what covers them, and 10% is only a starting point. To count grout joints, add the joint width to each tile dimension.
Frequently asked questions
How many tiles do I need for a room?
Divide the floor area by the area of one tile and round up. A 4 m × 3 m room is 12 m². With 60 × 60 cm tiles (0.36 m² each) that is 33.33, so 34 tiles for the bare floor, before any waste allowance.
How much extra tile should I buy?
The waste allowance covers cuts and breakage. Many suppliers suggest around 10% for a straight layout and more for diagonal or patterned layouts. The calculator starts at 10% as an example value and lets you change it from 0 to 100.
Does the calculator allow for grout joints?
No. It treats each tile as the size you enter and packs them edge to edge. To count joints, add the joint width to the tile length and width before entering them.
How is the waste added, and why does it round up?
The waste percentage is applied to the exact, unrounded tile count, and the total is then rounded up once. For the example room that is 33.33 × 1.10 = 36.67, so 37 tiles. Rounding up applies to tiles and boxes alike because you cannot buy part of either.
What does the leftover figure mean?
It is the tiles you will have after laying the floor: whole boxes times tiles per box, minus the tiles the bare floor needs. It includes your waste allowance plus any extra from rounding up to full boxes.