Tile Calculator (Metric)
Enter your room size, tile size, and a waste factor to get the tiles and boxes you need for a floor or wall.
What your result means
Tiles to buy already includes your waste, so that's the number you order. Boxes assume about 10 tiles per box, so check your box label and round to whole boxes. Buy it all in one dye lot, and keep a few spares back for repairs since colors drift between batches.
How to use this calculator
- Measure the room or wall in feet.
- Check tile box for tile dimensions in inches.
- Enter tile size and waste percentage (10% standard, 15% for diagonal layouts).
- The calculator returns total tiles needed and boxes to purchase.
- Always buy at least one extra box for future repairs.
The formula
Multiply room length by width for square feet, convert to square inches by multiplying by 144, then divide by one tile's square inches for the base count. Add your waste percentage, round up, then divide by tiles per box (about 10) and round up again.
Worked example
Say you're tiling a 12 by 3 m bathroom floor with 12-inch tiles and 10% waste. Enter the values and you'll get 120 base tiles, 132 with waste, and about 14 boxes at 10 tiles per box. Grab a 15th box and set it aside for repairs down the road.
Tiles per square foot by tile size
| Tile size | Tiles per sq ft | Tiles per 9.3 m² |
|---|---|---|
| 4 x 10.2 cm | 9 | 900 |
| 6 x 15.2 cm | 4 | 400 |
| 12 x 30.5 cm | 1 | 100 |
| 12 x 61 cm | 0.5 | 50 |
| 18 x 45.7 cm | 0.44 | 45 |
| 24 x 61 cm | 0.25 | 25 |
Tips & gotchas
- 10% waste is the standard for a rectangular room with a straight tile layout.
- Bump it to 15-20% for diagonal, herringbone, or a room with a lot of angles.
- Buy from one dye lot. Tile color drifts between batches and you won't match it later.
- Check tile thickness if you're tying into existing flooring, or you'll get a lip at the transition.
- Keep a few loose tiles aside, out of the box, for emergency swaps.
Frequently asked questions
How do I calculate tile coverage?
Divide the room's square inches by one tile's square inches, add your waste percentage, and round up. The calculator handles it for you.
What is a normal waste percentage for tile?
10% for a straight layout, 15-20% for diagonal or herringbone.
How many tiles come in a box?
It depends on tile size. 12-inch tiles usually run 10 to a box, but check the box before you order since it varies.
Should I buy extra tiles?
Yes, at least 10% over. Set aside 5-10 spares for future repairs, since matching a dye lot later is tough.
Can I use this for a backsplash?
Yes. Treat the backsplash as the area: enter the wall length times height instead of the floor size.
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