Tiles come in boxes, and the layout you've chosen changes the waste more than the room size does. Diagonal costs half again what straight does — and almost every calculator applies a flat 10% regardless.
Floors, walls and splashbacks. Enter the area, the tile size and how you're laying it — we'll work out whole boxes.
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Tiles come in boxes, so the count is only ever whole boxes. What moves the number is the layout: a diagonal lay costs about half again in waste what a straight lay does, because every tile meeting a wall is cut on the bias. Almost every other calculator applies a flat 10% regardless, which over-orders straight jobs and under-orders diagonal ones. Tell this one how you are laying it and the allowance follows.
Working from a wall pushes all the accumulated error into the far corner and leaves a sliver of cut tile in the most visible place. Set out from the centre, dry-lay a row first, and adjust so the cuts at each end are equal and reasonably wide. Buy every box in one order from one batch as well — going back for two more boxes next week is how a floor ends up with a visible patch.
Adhesive and grout are separate, and their coverage depends on tile size, trowel notch and how flat the substrate is — use the grout calculator for one and ask the tile shop for the other. Trim, edging and movement joints are separate too: external corners want trim, and any run over about 8 m or across a doorway wants a movement joint. And check the substrate before buying anything, because tiles fail from what is under them far more often than from the tiles themselves — a floor that flexes will crack grout no matter how good the tiling is.
It depends on the layout rather than the room. Straight lay in a square room is around 10%; a diagonal lay is about half again as much, because every perimeter tile is cut on the bias. Complex rooms with alcoves and returns need more than simple ones.
The centre. Starting at a wall pushes all the accumulated error into the far corner and leaves a sliver of cut tile in the most visible spot. Dry-lay a row first and adjust so the cuts at both ends are equal.
In any run over about 8 m, and across doorways. External corners also want trim. Neither is included in a tile count, and both need buying separately.
Yes, until the job is signed off and ideally beyond. Offcuts and spare tiles are the only exact-match material you will ever have — a later batch will not match.