Floors & walls
Tile calculator
How many tiles and boxes to buy for a floor or a wall: the area, the space each tile takes with its grout joint, and a waste allowance for cuts that suits the layout.
Tiles to order
600 × 300 mm tiles, straight lay, 4.32 m².
- Area to tile4.32 m²5.5 tiles per m² with 3 mm joints
- Tiles needed2723.6 to cover + 10% for straight lay
- Boxes to buy48 tiles a box · 5 tiles spare
| Item | Value |
|---|---|
| Tile size | 600 × 300 mm |
| Layout and waste | straight lay, 10% |
| Tiles to cover the area exactly | 23.6 |
| Tiles with waste | 27 |
| Boxes | 4 × 8 = 32 tiles |
| Area bought (tile faces) | 5.76 m² (62 ft²) |
Buy every box in one order and check that the batch (shade) numbers on the boxes match. Keep a few spare tiles for repairs.
How to use the tile calculator
Enter the floor or wall as one or more rectangles (length × width, or length × height for a wall). Split an L-shaped room into two, and add a rectangle with Leave this out ticked for anything you will not tile around, such as a bath or a fitted unit.
Give the tile's length and width and the grout joint. Each tile then takes up its own size plus one joint in each direction, which is why wide joints mean slightly fewer tiles.
The layout decides how much is lost to cuts. A straight grid wastes least; brick bond is similar; a diagonal layout cuts every tile along the edges; herringbone needs angled cuts at every wall. The waste allowance also covers breakages and a few spares for later repairs. Last, enter what a box holds, as a tile count or the area printed on it, and the calculator rounds up to whole boxes.
Worked example
A 2.4 × 1.8 m bathroom floor is 4.32 m². A 600 × 300 mm tile with a 3 mm joint takes up 0.603 × 0.303 = 0.183 m², so 23.6 tiles cover the floor exactly. Adding 10% for a straight layout makes 26.01, rounded up to 27 tiles. At 8 tiles a box that is 4 boxes, 32 tiles, with 5 to spare.
Waste allowances and batches
Tile retailers publish similar rules of thumb. Tile Mountain adds 10% for a straight lay, 10–15% for brick bond and 15% for diagonal and herringbone; NC Tiles & Bathrooms uses 10% as standard, 15% for diagonal and 25% for herringbone, and more for large-format tiles. This calculator's 20% for herringbone sits between the two. Both retailers warn that tiles from different production batches can differ in shade, so buy everything in one order and check the batch numbers on the boxes match.
Sources
- Tile Mountain, How many tiles do I need?: wastage by layout, and ordering every box in one batch.
- NC Tiles & Bathrooms, How to measure a room for tiling: 10% standard wastage, 15% for diagonal, 25% for herringbone, more for large-format tiles.
Questions
How many 600 × 600 mm tiles do I need for 10 m²?
With 3 mm joints each tile takes up 0.603 × 0.603 m, about 0.364 m², so 27.5 tiles cover 10 m² exactly. With 10% for a straight layout that is 31 tiles. Large tiles leave bigger offcuts, so many people allow a little more.
How many 12 × 24 in tiles are in 100 square feet?
Each tile is 2 ft², or about 2.03 ft² with a 1/8 in joint, so about 49 tiles cover 100 ft². With 10% waste for a straight layout that is 55 tiles; with 20% for herringbone it is 60.
Why does herringbone need so much extra?
The tiles meet the walls at an angle, so every tile along every edge is cut, and the offcuts are rarely the right shape to use elsewhere. Retailers' allowances for it range from 15% to 25%.
Should I count the grout joints?
The calculator already does: each tile is counted with one joint width added to its length and width. With small tiles and wide joints the difference is noticeable; with large tiles it is small.
How many spare tiles should I keep?
The waste allowance covers cuts and breakages, and the boxes are rounded up, so there are usually a few left over. Keep them, in their box with the batch number, for repairs: a later batch may not match.