Tile Calculator

How to use the tile calculator

1. Choose Metric (m, cm, mm) or Imperial (ft, in).
2. Under Surface to tile, pick Length × width and enter both dimensions (metres + centimetres, or feet + inches), or pick Known area if you already have the square metres or square feet, for example from the flooring and square footage calculator for an L-shaped room.
3. Enter the Tile length and Tile width (cm or in) and the Grout joint width (mm or in). The defaults are a 60 × 30 cm tile with a 3 mm joint, or a 24 × 12 in tile with a 1/8 in (0.125 in) joint.
4. Set the Waste allowance (%) and the number of Tiles per box printed on the box. Optionally add the Price per box.
5. Read the Tiles without waste, the Tiles with waste, the Boxes to buy, and what you will actually bring home. Every step of the calculation is listed below the results. Reset defaults puts the starting values back.

Everything is computed in your browser; nothing is uploaded.

How the number of tiles is calculated

Each tile takes up its own size plus one grout joint in each direction:

Tile footprint = (tile length + joint) × (tile width + joint)

Tiles = area ÷ tile footprint × (1 + waste %), rounded up to a whole tile, then boxes = tiles ÷ tiles per box, rounded up to a whole box.

Example: a 3 × 2.5 m bathroom floor is 7.5 m². A 60 × 30 cm tile with a 3 mm joint occupies 0.603 × 0.303 = 0.1827 m², so the floor needs 41.05 tiles. With 10% waste that is 45.15, rounded up to 46 tiles; at 8 tiles per box, 5.75 boxes means 6 boxes (48 tiles). In imperial units, a 10 × 8 ft floor (80 sq ft) with 12 × 24 in tiles and 1/8 in joints needs 39.4 tiles, 44 with 10% waste, so 6 boxes of 8.

This area method is the one used by tile shops. It does not draw the layout, so for very small or oddly shaped rooms, a quick sketch of rows and cut tiles is a good cross-check.

How much waste to allow

Waste covers cut tiles along the walls, breakage, mistakes and a few spares:

• 10% for a straight (grid or brick) layout in an ordinary room;
• 15% for a diagonal layout, herringbone, many corners or pipes, or small rooms where a high share of tiles is cut;
• 5% only for large, simple rectangular rooms with small tiles;
• more for natural stone or handmade tiles, which vary and chip.

Large-format tiles (60 × 120 cm, 24 × 48 in and above) produce big offcuts that often cannot be reused, so stay at 10–15% even in simple rooms.

Buying tips

• Buy all boxes at once and check that the batch (lot) and shade codes match: tiles from different batches can differ visibly in colour and even in size (calibre).
• Keep at least one full box after the job for future repairs; discontinued tiles are hard to find.
• Many shops take back unopened boxes: ask before you buy, and round up rather than down.
• Also buy adhesive (thinset) and grout for the same area; their coverage is printed on the bag and depends on the trowel notch and joint size.
• The joint width, adhesive and underlayment recommended by the tile and adhesive manufacturers, and local building codes for wet rooms, prevail over this estimate.