How much wastage should I allow?

10% for a straightforward grid layout with few cuts, 15% for diagonal or herringbone patterns with more cuts and breakage, and up to 20% for small tiles in irregular rooms. Always keep a few spare boxes for future repairs.

Should I round up boxes even if I am close?

Yes. Tiles come in batched dye-lots, so a box bought later may not match. Rounding up to whole boxes ensures one batch and leaves spares for breakages and repairs.

Can I use this for wall tiles?

Yes — enter the wall area instead of floor area, or use the wall’s height and width as the “length” and “width”. The tile size and wastage logic is the same for walls and floors.

How much wastage should I allow for a diagonal layout?

Diagonal and herringbone layouts cut more tiles at the edges and waste more, so allow 15% rather than 10%. For very small tiles in an irregular room, or large format tiles that break easily, consider 20%. The wastage field is editable for exactly this reason.

Can I use this for wall tiles and splashbacks?

Yes. Enter the wall area as length × width (or the wall’s height and width), and the tile size and box count as on the packaging. The logic is identical for walls and floors — only the area source differs.

Cooking & DIY/Home Calculators

Tile Quantity Calculator

Tiling a floor or wall means buying enough tiles to cover the area plus a wastage allowance for cuts, breakages and future repairs — but not so many that you store boxes you cannot return. This calculator takes the area (or the room dimensions), the tile size and a wastage percentage, and returns the number of tiles and the boxes to buy.

Enter the room length and width (or the area directly), the tile dimensions in centimetres, the tiles per box, and a wastage percentage — 10% is standard for a straight layout, 15% for diagonal or patterned layouts. The calculator works out the area, the tile count with wastage, and rounds up to whole boxes.

It is the calculation that gets a tiling job done in one purchase — the tile count with a wastage allowance, rounded up to whole boxes from one batch, so there are spares for cuts and future repairs and no dye-lot mismatch.

Length (m)

Width (m)

Tile width (cm)

Tile height (cm)

Tiles per box

Wastage%

Enter your values to see the result.

How this is calculated

The area to tile is the room length × width (or a directly entered area). The area of one tile is (tile width in cm ÷ 100) × (tile height in cm ÷ 100), in square metres. The bare tile count is the area ÷ tile area, and the wastage percentage is added on top — 10% for a straight grid layout, 15% for diagonal or patterned layouts with more cuts. The result is rounded up to a whole tile, then to whole boxes by dividing by the tiles-per-box and rounding up again.

Rounding up to whole boxes matters because tiles are batched by dye-lot: a box bought later may be a slightly different shade, visible once laid. Buying the whole job from one batch avoids that, and the spare boxes left over are worth keeping for future repairs — a chipped tile replaced years later needs a matching piece. The extra-tiles-for-spares line shows how many of the bought tiles are the wastage allowance.

The model assumes a rectangular area and a single tile size. For multiple tile sizes in a pattern, calculate each size’s count separately. For walls, use the wall’s height and width as the “length” and “width”. Very small tiles (mosaics) on sheets, or very large format tiles with high breakage, may need a higher wastage percentage than the default — adjust the field to match the job.

Worked example

A 4 m × 3 m floor, 30 cm × 30 cm tiles, 12 per box, 10% wastage.

1Area = 4 × 3 = 12 m².
2Tile area = 0.30 × 0.30 = 0.09 m².
3Bare tiles = 12 ÷ 0.09 = 133.3 → 134.
4With 10% waste = 134 × 1.10 = 147.4 → 148 tiles.
5Boxes = ceil(148 ÷ 12) = 13 boxes (156 tiles).

Frequently asked questions

How much wastage should I allow?: 10% for a straightforward grid layout with few cuts, 15% for diagonal or herringbone patterns with more cuts and breakage, and up to 20% for small tiles in irregular rooms. Always keep a few spare boxes for future repairs.
Should I round up boxes even if I am close?: Yes. Tiles come in batched dye-lots, so a box bought later may not match. Rounding up to whole boxes ensures one batch and leaves spares for breakages and repairs.
Can I use this for wall tiles?: Yes — enter the wall area instead of floor area, or use the wall’s height and width as the “length” and “width”. The tile size and wastage logic is the same for walls and floors.
How much wastage should I allow for a diagonal layout?: Diagonal and herringbone layouts cut more tiles at the edges and waste more, so allow 15% rather than 10%. For very small tiles in an irregular room, or large format tiles that break easily, consider 20%. The wastage field is editable for exactly this reason.
Can I use this for wall tiles and splashbacks?: Yes. Enter the wall area as length × width (or the wall’s height and width), and the tile size and box count as on the packaging. The logic is identical for walls and floors — only the area source differs.

Related calculators

Method: area ÷ tile area × (1 + wastage), rounded up to whole tiles then whole boxes. Wastage defaults to 10% (straight layout) or 15% (patterned). Last updated: September 2026.

These results are general estimates from established formulas and conversion factors. Paint coverage, tile yields, concrete volumes, fuel economy, oven behaviour and clothing and shoe sizes vary by product, surface, vehicle, oven and brand. Always confirm with your supplier, the product label or the brand’s own size chart before buying or acting on a calculation.