How is the tile count calculated?

The area to cover is divided by the area of one tile, multiplied by one plus the waste percentage, then rounded up to whole tiles.

What waste percentage should I use?

Around 10% for straight layouts; 15–20% for diagonal or herringbone patterns and rooms with many cuts. Keep a few spares for repairs.

How do I convert tiles to boxes?

Divide the tiles needed by the number of tiles per box and round up. The box quantity is on the packaging.

Does it account for grout lines?

Grout lines are small and usually ignored; the waste percentage absorbs them. For very large tiles you can add the joint width to the tile size.

Can I use it for walls?

Yes. Enter the wall area instead of the floor area; the maths is the same.

Can I share a calculation?

Yes. Use Share to copy a link that reopens the calculator with the same area and tile size.

Tile calculator

Enter the area to cover in metres and one tile's size in centimetres, then add a waste percentage for cuts and breakage. The calculator shows the tiles needed, the floor area, the count before waste, and the area of a single tile.

Use it to see how many tiles to buy for a given area and tile size, including a margin for waste.

Tiles needed

147

Area to cover: 12 m²
Before waste: 134
Area per tile: 0.09 m²

The result updates as you type. The headline is the total to buy; the before-waste figure shows the bare minimum and the difference is your spares.

How does it work?

Tile dimensions are converted from centimetres to metres before the area is worked out. The count always rounds up to whole tiles.

Tile count formula

N = \left\lceil \frac{A}{a}\times\left(1+\tfrac{w}{100}\right) \right\rceil

N: Tiles needed, rounded up.
A: Area to cover in square metres.
a: Area of one tile in square metres.
w: Waste allowance as a percentage.

A 4 m × 3 m floor is 12 m². With 30 cm × 30 cm tiles (0.09 m²) that is 134 tiles; adding 10% waste rounds up to 147.

Method & sources

The area is entered in metres; the tile size is entered in centimetres. Tiles are counted by area, not by laying pattern. A waste percentage covers cuts, breakage, and future spares.

Sources

Where this method comes from — use these references to understand the formula, assumptions, and limits.

Tile installation — coverage and waste factor — Ceramic Tile Alliance, verified 2026-06-10

How we calculate

The area is entered in metres; the tile size is entered in centimetres.
Tiles are counted by area, not by laying pattern.
A waste percentage covers cuts, breakage, and future spares.
Counts always round up to whole tiles.

Rounding

Tile counts round up to whole tiles; areas are shown to a few decimals. The calculation uses full precision.

What this calculator does

Tiles are sold by the box but planned by area. This calculator divides the area to cover by the area of one tile, adds a waste percentage for cuts and breakage, and rounds up to whole tiles so you know how many to buy.

How to use it

Enter the length and width of the area in metres.
Enter the tile length and width in centimetres.
Set a waste percentage (10% is typical; more for diagonal layouts).
Read the tiles needed and divide by the box quantity to get boxes.

A worked example

A 4 m × 3 m floor is 12 m². With 30 cm × 30 cm tiles, each tile covers 0.09 m², so the bare minimum is 134 tiles. Adding 10% waste rounds up to 147 tiles.

Choosing a waste percentage

Straight layouts on a simple rectangular room need about 10%. Diagonal or herringbone patterns, lots of cuts, or large-format tiles can need 15–20%. Keeping a few spares for future repairs is wise.

Common mistakes

Entering the tile size in metres instead of centimetres.
Forgetting waste and buying the exact minimum.
Counting boxes without checking the tiles-per-box figure.

When it's useful

Planning a floor, splashback, bathroom, or patio — any tiling job where you need to know how many tiles and boxes to order before you start.

FAQ

How is the tile count calculated?: The area to cover is divided by the area of one tile, multiplied by one plus the waste percentage, then rounded up to whole tiles.
What waste percentage should I use?: Around 10% for straight layouts; 15–20% for diagonal or herringbone patterns and rooms with many cuts. Keep a few spares for repairs.
How do I convert tiles to boxes?: Divide the tiles needed by the number of tiles per box and round up. The box quantity is on the packaging.
Does it account for grout lines?: Grout lines are small and usually ignored; the waste percentage absorbs them. For very large tiles you can add the joint width to the tile size.
Can I use it for walls?: Yes. Enter the wall area instead of the floor area; the maths is the same.
Can I share a calculation?: Yes. Use Share to copy a link that reopens the calculator with the same area and tile size.

Related calculators

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