Tile Calculator
Calculate how many tiles you need for a floor or wall. Enter room dimensions and tile size to get tile count, boxes needed, and grout quantity.
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How to use this calculator
Tile area = tile length × tile width (accounting for grout joint). Total tiles = room area with waste divided by single tile area.
- 1
Enter the room or wall dimensions in metres.
- 2
Enter the tile size in centimetres and the grout joint width in millimetres.
- 3
Set the waste percentage: 10% for straight lay, 15% for diagonal.
- 4
Enter tiles per box to get the number of boxes to purchase.
Frequently asked questions
What formula does this tile calculator use?
The area covered by one tile includes its joint: (tile length + joint) × (tile width + joint). Raw tiles = room area ÷ that cell area, and the order quantity is raw tiles × (1 + waste%) rounded up. A 4 × 3 m room with 60 × 30 cm tiles and 3 mm joints needs 66 tiles exactly, and 73 with the default 10% waste.
How is the number of boxes calculated?
The box count divides the waste-adjusted tile count, not the area, by tiles per box and rounds up. For 73 tiles at 10 per box that is 8 boxes. Enter 0 for tiles per box to hide the line. If your boxes are labelled in square metres, use the tile size to work out how many tiles that is.
How does the grout estimate work?
It starts from a baseline of about 1 kg per m² for 3 mm joints between 60 × 30 cm tiles, and scales it in proportion to the joint width and to the length of joint per square metre, which rises as tiles get smaller. The default room gives about 12.0 kg; 10 × 10 cm tiles in the same room give about 48.0 kg. Joint depth, tile thickness and grout density are not known, so use the grout manufacturer’s coverage chart for what to buy.
Which tile and joint units should I use?
Tile length and width are in centimetres, the grout joint is in millimetres and the room is in metres. Entering a 60 cm tile as 600 would be read as 600 cm and produce a tiny tile count, so check the units on each label.
Can I use it for walls?
Yes, treat the wall as the length and width of the room. The tool does not subtract windows, doors, niches or fixtures, so enter smaller areas or calculate each wall piece separately. Several rectangles can be added together by running them one at a time.
Does the waste allowance depend on the layout?
No. It is a single percentage you choose, applied to the raw tile count whatever the pattern. Diagonal, herringbone and similar layouts need more cuts, so set a larger value for them. The tool cannot see your room shape or the number of cuts.
Why is the exact count different from room area ÷ tile area?
Because the joint is included in each tile’s footprint. For the default room, 12 m² ÷ the plain 0.18 m² tile gives 66.7, but the 3 mm joints enlarge each cell to 1,827.1 cm², so the exact figure is 65.7, shown rounded up as 66.
Does it check adhesive, substrate or movement joints?
No. It counts tiles, boxes and an estimated grout weight only. Adhesive, waterproofing, substrate preparation and movement joints depend on the product and the room, so follow the manufacturer’s instructions or ask the tile supplier.
Tile calculator — tile count, boxes and grout weight
Why the joint belongs in the tile area
Tiles are laid with a gap between them, so every tile in the finished surface claims slightly more area than its own face. The calculator adds the joint width to both tile dimensions before dividing the room area by the result. For a 60 × 30 cm tile with a 3 mm joint, the cell is 60.3 × 30.3 cm, or 1,827.1 cm², instead of 1,800 cm². That small difference reduces the count a little, which is why a 12 m² room needs 66 tiles rather than the 67 you would get by ignoring the joint. The waste percentage is then added to the raw figure before it is rounded up.
Worked examples
The table compares four rooms run through the calculator, each with its own tile size, joint, waste and box size. The last row uses 10 cm square tiles in the default room to show how the count and grout estimate grow when tiles shrink.
| Room and tile | Exact tiles | With waste | Boxes | Grout estimate |
|---|---|---|---|---|
| 4 × 3 m, 60 × 30 cm, 3 mm joint, 10% waste, 10 per box | 66 | 73 | 8 | ~12.0 kg |
| 2.5 × 2 m, 30 × 30 cm, 2 mm joint, 15% waste, 11 per box | 55 | 64 | 6 | ~4.4 kg |
| 3 × 2.4 m, 60 × 60 cm, 3 mm joint, 10% waste, 4 per box | 20 | 22 | 6 | ~4.8 kg |
| 4 × 3 m, 10 × 10 cm, 3 mm joint, 10% waste, 10 per box | 1,132 | 1,245 | 125 | ~48.0 kg |
Boxes come from tiles, not area
The box count divides the rounded tile total by the number of tiles in a box. In the second row, 64 tiles at 11 per box is 5.8, so 6 boxes. The third row shows the effect of small boxes: 22 tiles at 4 per box is 5.5, rounded to 6 boxes, which gives 24 tiles in hand for a requirement of 22. Check the tile count on the carton rather than the area printed on it, since the tool expects a count.
How the grout number scales
The grout weight is a rough guide. It grows in direct proportion to the joint width, so doubling the joint doubles the estimate, and it grows with the amount of joint line in each square metre, which is why the same room needs about 48 kg with 10 cm tiles but about 12 kg with 60 × 30 cm tiles. The baseline is the tool’s own rule of thumb and ignores joint depth and the product’s density, so treat the figure as a ballpark and consult the grout manufacturer’s coverage tables.
What it does not cover
The tool covers rectangular areas and a single waste percentage. It does not subtract openings, work out cuts around obstacles, or tell you how much adhesive, backer board or sealant to buy. For an L-shaped or broken-up area, calculate each rectangle separately and add them up. Check your tile supplier’s recommendations for joint width and the setting materials the tiles need.
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Results are estimates for informational purposes only and do not constitute professional financial, medical, legal, or technical advice. Read full disclaimer →