← 🏠 Homeowners and DIYers toolkit
Tile Calculator
How many tiles, and how many boxes, for a floor or wall.
Part of the 🏠 Homeowners and DIYers toolkit, with more tools made for the job.
Use this instead of length and width.
Leave empty for 10%. Guides often say 10% for a straight layout and 15% or more for diagonal.
Gives the number of boxes.
Type the area and the tile size, and the number of tiles to buy appears here.
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Enter the length and width of the area (or its size), the size of one tile and an allowance for cuts. This gives the number of tiles and the boxes to buy.
Tiling always loses some tiles. They break, they need cutting around edges, pipes and corners, and a diagonal layout wastes more than a straight one. So the number you buy is the area divided by the tile size, plus a percentage on top, rounded up to whole boxes. Guides often use 10 percent for a straight layout and 15 percent or more for diagonal, though the figures vary by source, tile size and room shape, so you can change it.
How it’s worked out
- Area is length times width, or the area you type directly.
- Tiles to cover it exactly is the area divided by the area of one tile (width times height).
- The allowance is added to that number, which is then rounded up to whole tiles.
- Boxes are the tiles divided by the tiles in a box, rounded up. Grout joints are not taken off, which keeps the order on the safe side.
A 3 m by 2.5 m floor is 7.5 square metres. With 30 cm tiles (0.09 square metres each) that is about 83 tiles, and with 10 percent extra it is 92 tiles, or 9 boxes of 11.
Common mistakes
- Buying the exact number. Even a careful tiler breaks some, and a spare few from the same batch are useful for repairs later.
- Mixing batches. Tiles from different production runs can differ in shade, so buy all you need at once.
- Forgetting the layout. Diagonal, herringbone and large-format tiles waste more than a straight layout.
- Measuring one wall. Add up every wall or area you are tiling, and take off anything you will not tile, like a bath panel.
Questions
How much extra should I buy?
Guides give different figures, often around 10 percent for a straight layout and 15 percent or more for diagonal or awkward rooms. Ask your supplier, and use more for a first-time job.
Do I take off the grout joints?
No. Tile sizes already include the joint on most products, and ignoring it keeps your order slightly high, which is safer.
What about walls?
Use the same calculation for each wall: width times height, minus windows and doors. Add the areas together.
How do I work out adhesive and grout?
The amounts depend on the product and the tile size, and the bag or tub gives a coverage figure. Use the area to buy here with that figure.
Where the method comes from
Estimates only
These are estimates and general information, not building, safety, legal or professional advice. Materials, coverage, waste and rules vary by product, project and place, so check the maker's instructions and your local rules, and use a qualified person for gas, electrical and structural work.
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