Tile Calculator
How many tiles a floor or wall needs, with the grout joint accounted for. Add the tiles per box and you get a box count rather than a number to divide in your head.
Switching units keeps your measurements. Nothing is reset.
Areas
Your tile
The gap between tiles. Added to both dimensions.
Optional. Add it to get a box count.
Waste allowance
10% suits a straight layout in a squarish room.
Offcuts, breakages, pattern matching and the occasional damaged piece all mean you use more material than the bare area. Keeping a few spare pieces for future repairs is also normal.
This is a planning allowance, not a rule. Adjust it for your layout, your material and your own tolerance for a second trip to the store.
Estimated cost
Cost uses the price you enter. This product never shows invented market prices.
Your result appears here
Enter your measurements to see how much material to buy.
How to use this calculator
- 1
Measure the surface. A bathroom floor with a shower area is two shapes; add a second area rather than averaging.
- 2
Measure an actual tile rather than trusting the box. A tile sold as 12 inch is often 11.8 inch, and that difference compounds across a floor.
- 3
Enter your grout joint. It is added to both dimensions, because each tile occupies its own size plus one joint.
- 4
Add the tiles per box if you want the answer as boxes, then adjust the waste allowance for your layout.
A worked example
A 100 ft² floor in 12 in × 12 in tiles with a 1/8 in grout joint, 12 tiles to a box and a 10% waste allowance:
Measured area
100 ft²100 ft²
Add the waste allowance
100 ft² × 1.1110 ft²
Divide by the coverage of one package
110 ft² ÷ 12.25 ft²8.98
Round up to whole packages
round up 8.989
Coverage you are buying
9 × 12.25 ft²110.3 ft²
You will need
9 boxes
This example is produced by running the calculator above, so it always matches what the tool does.
The formula
Each tile occupies its own width plus one joint, by its own length plus one joint. That effective area is what the floor is divided by, not the bare tile size. The measured area has the waste allowance applied first, and the result is rounded up to whole tiles and then to whole boxes, because neither can be bought in part.
Tiling well
The layout drives the waste, not the room
A straight grid in a rectangular room wastes least. Diagonal layouts cut every edge tile at 45 degrees, and herringbone wastes more again. If you are laying anything other than a straight grid, raise the allowance well above the default.
This calculator assumes a straight layout
The maths here is for a straight grid. It does not model diagonal, running bond or herringbone cutting patterns, and it would be dishonest to imply otherwise. For those layouts, treat the result as a floor and add more.
Buy the spares now, not later
Tile batches vary in shade. A box kept back from the same batch is the only reliable way to replace a cracked tile in two years time.
Common questions
- How many tiles do I need?
- Divide the area by the space one tile occupies, including its grout joint, then round up and add an allowance for cuts. A 100 square foot floor in 12 inch tiles with a 1/8 inch joint needs about 108 tiles at 10% waste.
- Does the grout joint really matter?
- It reduces the tile count slightly, because each tile covers a little more floor than its own size. On a large floor with a wide joint the difference is several tiles, which is why it is included here.
- How much extra should I buy for a diagonal layout?
- More than the default. A diagonal layout cuts every perimeter tile and typically wastes noticeably more than a straight grid. Raise the allowance rather than trusting a figure calculated for a straight layout.