Tile Calculator

Last updated: 2026-05-18

Why Getting the Count Right Matters

Buying the right number of tiles avoids two expensive mistakes: running short mid-project (when a discontinued colour may be impossible to match) or buying so many that you store boxes for years. This calculator accounts for grout gaps and a waste factor so you order confidently the first time.

How It Works

Each tile occupies slightly more floor space than its face dimensions because of the grout gap on each edge:

A_t = (T_L + G) \times (T_W + G)

N = \left\lceil \frac{A_{\text{room}}}{A_t} \right\rceil

N_w = \left\lceil N \times (1 + W_f) \right\rceil

N_{\text{box}} = \left\lceil \frac{N_w}{n_b} \right\rceil

where $T_L$ and $T_W$ are tile length and width, $G$ is grout gap, $A_{\text{room}}$ is room area, $W_f$ is waste factor (entered as a percentage — e.g. 10% — and converted to a decimal ratio internally), and $n_b$ is tiles per box. ⌈·⌉ is the ceiling function — rounds up to the nearest whole number (you can't buy a fraction of a tile). All dimensions must be in the same unit — the calculator handles conversion automatically.

Choosing the Right Waste Factor

Laying pattern	Waste factor
Straight lay (parallel to walls)	10%
Diagonal lay (45°)	15%
Herringbone or chevron	20%
Complex mosaic, pinwheel	20–25%

Add an extra 5% for rooms with many internal corners, columns, or doorway cuts. If the tile range may be discontinued, buying an extra box (5–10% more) is cheap insurance.

Grout Gap Reference

Tile type	Common grout gap
Large format (60 × 60 cm+)	2–3 mm
Standard floor tile (30 × 30 cm)	3–5 mm
Wall tile	2–3 mm
Mosaic (under 10 cm)	1–2 mm
Rustic / handmade tile	5–10 mm

Tiles Per Box

Boxes typically contain 6–12 tiles for large formats, and 25–50 for smaller tiles. Manufacturers print tile count per box and m² per box on the packaging — enter whichever you have. The calculator always rounds up to whole boxes.

Frequently Asked Questions (FAQ)

How do I calculate the number of tiles I need?

Divide the room area by the area of one tile (including the grout gap on each edge). For example, a 4 m × 3 m room is 12 m². A 60 cm × 30 cm tile with a 3 mm grout gap covers (0.603 × 0.303) = 0.1827 m² per tile. You need ceil(12 / 0.1827) = 66 tiles without waste. Always add a waste factor (typically 10%) to cover cuts and breakage: 66 × 1.10 = 73 tiles. Round up to whole boxes.

What waste percentage should I add for tiles?

Use 10% for a straight lay (rows parallel to walls). Use 15% for a diagonal lay (tiles at 45°) because every edge tile must be cut at an angle. Use 20% for complex patterns like herringbone, pinwheel, or mosaic.

Add an extra 5% for rooms with many internal corners, doorways, or columns. A small extra batch of the same tile (especially a custom colour) is almost impossible to match exactly later — always buy slightly more than you think you need.

How does the grout gap affect the number of tiles?

The grout gap increases the effective area each tile occupies on the floor. With a 3 mm gap, a 600 mm × 300 mm tile takes up 603 mm × 303 mm = 0.1827 m², rather than 0.18 m² without a gap. For a 12 m² room that is about 65.7 vs. 66.7 tiles — a small difference for large floor tiles.

For small mosaic tiles (e.g. 50 mm × 50 mm with a 2 mm gap), the grout gap adds 4% to each tile dimension and significantly changes the count. Always enter the actual grout gap for accuracy.

How do I tile an L-shaped room?

Split the room into two rectangles and calculate each section separately, then add the totals. For example, an L-shaped room can be split into a 5 m × 3 m section and a 2 m × 2 m section: 15 m² + 4 m² = 19 m² total. Plan the tile layout from the centre of the main area outward so that cut tiles at the edges are equal in size. Avoid starting from a wall — you may end up with a narrow sliver (less than half a tile width) at the opposite edge.

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