Floor Tile and Flooring Calculator

How many tiles do you need?

The area is increased by the waste allowance and divided by the area of one tile: tiles = area × (1 + waste) / (width × length). The result is rounded up because you cannot buy part of a tile. Tiles are sold by the box, so the count is divided by the tiles per box and rounded up again.

How much waste to allow

Tiles are cut at walls and thresholds and some will break. Allow roughly 5 to 10 percent for a straight lay and 10 to 15 percent for diagonal or herringbone patterns. Rooms with many corners need more. Keeping a few spare tiles from the same batch helps with later repairs.

How grout is calculated

The joint length in one square metre is (width + length) / (width × length). Multiplying it by the joint width and depth gives the joint volume, and multiplying by density gives kilograms. Smaller tiles mean more joint length and more grout.

Example

A room of 5 m × 4 m is 20 m². With 10 percent waste it becomes 22 m². A 60 × 60 cm tile covers 0.36 m², so you need 62 tiles. At 4 tiles per box that is 16 boxes. With a 3 mm joint and 9 mm thickness you need about 2.9 kg of grout, and at 4 kg/m² about 80 kg of adhesive. Skirting comes to 17.1 m after deducting a 0.9 m door.

Limits

Adhesive and grout consumption depend on the product, the trowel notch and how flat the floor is. The defaults here are approximate, so check the product data sheet for firm figures. Split rooms that are not rectangular into parts and add the areas.