How much tile waste should I allow?

Allow about 10 percent for a straight brick or grid layout, and 15 percent for diagonal, herringbone or small-format patterns, which create more cuts and offcuts.

How do I count tiles for an odd-shaped room?

Split the surface into rectangles, calculate each one, and add the results. Then apply a single waste allowance across the total to cover cuts at the edges.

Tiles are sold by the box and shades vary slightly between batches, so buying whole boxes from one batch keeps the colour consistent and leaves spares for future repairs.

What is the Tile Calculator?

Calculate how many wall or floor tiles you need from the area and tile size, add a waste allowance and round up to whole boxes. Runs in your browser. It runs free in your browser on Gera Tools, with nothing uploaded.

Tile Calculator — Gera Tools

Name: Tile Calculator
Creator: Gera Tools
License: https://creativecommons.org/licenses/by/4.0/

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Tiling a wall or floor needs a tile count that allows for the cuts around edges and obstacles, then rounds up to whole boxes. This calculator does both from your surface size and the tile format you have chosen.

How it works

surface area = width × height
tile area    = (tile width cm / 100) × (tile height cm / 100)
tiles        = ceil(surface area / tile area)
to buy       = ceil(tiles × (1 + waste%))
boxes        = ceil(to buy / tiles per box)

The waste allowance covers the tiles you cut to fit edges and around fittings — offcuts are rarely large enough to reuse elsewhere.

Worked example

A 3 m × 2.4 m wall with 20 cm × 30 cm tiles, using 10 percent waste and 10 tiles per box:

Wall area = 7.2 m²
Tile area = 0.2 × 0.3 = 0.06 m²
Tiles = ceil(7.2 / 0.06) = 120, plus 10 percent = 132
Boxes = ceil(132 / 10) = 14 boxes

What to watch

Pattern drives waste. Straight layouts waste least; diagonal and herringbone layouts generate far more offcuts, so raise the waste percentage for them.

Keep a spare box. Colours shift between production batches, so a box kept back from the original batch is the only reliable match for a future repair.