Tile Calculator

Work out how many tiles you need, including a wastage allowance.

Tiles needed (with wastage)

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Bare minimum

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Spare for cuts

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Per tile

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Boxes to buy

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An estimate. Allow more wastage for diagonal layouts, large tiles or rooms with lots of cuts.

From area to tile count

Each tile covers a small area equal to its width times its height. Divide the surface you are tiling by that figure to get the bare number of tiles, then add a wastage percentage for cuts, breakages and future repairs.

tiles = area ÷ (tile width × tile height) × (1 + wastage)

Because tiles come in boxes, the realistic number to buy is rounded up to whole boxes. Buying a little over from a single batch protects you against running short mid-job, when a colour-matched top-up is hard to find.

Worked example

Covering 12 m² with 30 × 30 cm tiles means each tile covers 0.09 m², so you need about 134 tiles. Adding 10% for cuts and breakages brings it to 147 — about 13 boxes if a box holds 12.

Planning a tidy job

Most tiling mishaps come down to running out, or to mismatched batches. A quick estimate with a sensible wastage margin sidesteps both, and helps you budget before you reach the till.

Practical pointers

Layout drives wastage. Straight grids waste little; diagonal and herringbone patterns waste more.
Big tiles, bigger margin. A single bad cut on a large tile is a costly offcut.
One batch, kept spares. Buy together and store the leftovers with the batch number.

Frequently asked questions

How much wastage should I allow?

Around 10% is typical for a straight layout. Allow more — 15% or so — for diagonal patterns, lots of cuts around fixtures, or large-format tiles where offcuts are harder to reuse.

Do I measure the tile or the grout joints?

Use the nominal tile size. Grout joints are small and usually cancel out against the wastage allowance, so they are not worth modelling separately for an estimate.

Should I buy by the box?

Yes. Tiles are sold in boxes, so round up to whole boxes — and ideally buy from one batch, since colour and size can vary slightly between production runs.

Why keep spare tiles?

A cracked tile years later is far easier to replace if you kept a few from the same batch. Storing the leftovers (and the batch number) is well worth the shelf space.