Materials & quantities
Tile quantity & layout calculator
Compare an area allowance with a rectangular tile layout and box count.
Loading the local tool…
What a tile calculator does
A tile calculator works out how many tiles and boxes you need to cover a floor or wall from the room size, the tile size and the grout joint. This one gives two counts: an area estimate (room area ÷ tile area) and a layout count that places a straight grid from one corner and counts every cut edge piece as a full tile.
The difference matters most with large tiles. A 14 × 11 ft kitchen floor in 18 × 18 in tiles has an area estimate of 69 tiles, but a straight grid needs 80 pieces because the last column and row are narrow cuts. The calculator orders from the larger of the two counts, adds your waste allowance and rounds up to whole boxes.
As a rule of thumb, 12 × 12 in tile is 1 per square foot, 12 × 24 in is 0.5 and 24 × 24 in is 0.25. The tool grids straight and 50% offset layouts and sizes the edge pieces; diagonal and herringbone patterns use the area estimate with typical pattern waste shown, and still deserve a cutting plan.
How to use the tile quantity & layout calculator
- Choose Imperial or Metric. Room dimensions are entered in feet or metres; tile size and grout joint in inches or millimetres.
- Enter the room Length and Width. For an L-shaped room, split it into rectangles and run each one.
- Pick a Tile size preset (12 × 12 in through 600 × 1200 mm) or choose Custom and enter the Tile length and Tile width. Tile length runs along the room length, so swap the two values to compare orientations. Enter the Grout joint and Tile thickness.
- Choose the Layout pattern: straight grid, 50% offset, diagonal or herringbone. The count at that pattern's typical waste is shown beside the count from your own Waste allowance.
- Enter Tiles per box from the box label, the Adhesive coverage per bag and the Grout bag size from the product labels, and an optional price per box.
- Read the area estimate, grid pieces, tiles with waste, boxes to order, grout and adhesive bags, and, for a straight grid, the cut list of full, edge and corner pieces. Download the grid diagram as SVG, export a PDF or CSV, or copy the result.
Worked example
Imperial: A 12 × 10 ft room using 12 × 12 in tiles and no joints takes 120 tiles before waste.
Metric: A 3 × 3 m room using 600 × 600 mm tiles and no joints takes 25 tiles before waste.
How many tiles per square foot?
Divide 144 by the tile's face area in square inches. A 12 × 24 in tile is 288 in², or 2 ft², so you need 0.5 tiles per square foot. These figures ignore the grout joint, which makes them slightly conservative: with 1/8 in joints, 12 × 12 in tile covers about 2% more area per piece.
Some tiles sold by a nominal size are slightly smaller than the name suggests. Use the actual size printed on the box.
| Tile size | Tiles per ft² | Tiles per 100 ft² | ft² per tile |
|---|---|---|---|
| 3 × 6 in (subway) | 8 | 800 | 0.125 |
| 4 × 4 in | 9 | 900 | 0.111 |
| 6 × 6 in | 4 | 400 | 0.25 |
| 6 × 24 in (plank) | 1 | 100 | 1 |
| 6 × 36 in (plank) | 0.667 | 66.7 | 1.5 |
| 12 × 12 in | 1 | 100 | 1 |
| 12 × 24 in | 0.5 | 50 | 2 |
| 18 × 18 in | 0.444 | 44.4 | 2.25 |
| 24 × 24 in | 0.25 | 25 | 4 |
| 8 × 48 in (plank) | 0.375 | 37.5 | 2.667 |
| 24 × 48 in | 0.125 | 12.5 | 8 |
Metric tiles per square metre
In metric, divide 1,000,000 by the tile area in square millimetres. A 600 × 600 mm tile covers 0.36 m², so a square metre takes 2.78 tiles.
| Tile size | Tiles per m² |
|---|---|
| 100 × 300 mm | 33.33 |
| 200 × 200 mm | 25 |
| 300 × 300 mm | 11.11 |
| 300 × 600 mm | 5.56 |
| 600 × 600 mm | 2.78 |
| 600 × 1200 mm | 1.39 |
How much extra tile should I buy?
The allowances below are common rules of thumb, not standards. Straight lay produces the fewest cuts; diagonal and herringbone patterns cut a triangle or angle off every edge tile. Small rooms, lots of obstacles and fragile or expensive tile all justify more. Keep a few spare tiles after the job for future repairs, because the same shade may not be available later.
The calculator applies the allowance to the larger of the area and grid counts. For 77 tiles, 10% gives 85, 15% gives 89 and 20% gives 93.
| Layout | Typical allowance |
|---|---|
| Straight grid | 10% |
| Running bond (brick offset) | 10 to 15% |
| Diagonal | 15% |
| Herringbone or chevron | 15 to 20% |
Worked example: kitchen floor with 18 × 18 tiles
A 14 × 11 ft kitchen uses 18 × 18 in porcelain with 1/8 in joints, packed 5 to a box (box counts vary by product). The area estimate is 68.44 tiles, shown as 69. The grid needs 10 columns and 8 rows, 80 pieces, because the last column and row are strips about 5 in wide. With 10% waste the order is 88 tiles, or 18 boxes containing 90 tiles.
Orientation changes rectangular tile counts too. In an 8 × 5 ft bathroom with 12 × 24 in tile and 1/8 in joints, running the 24 in side along the 8 ft wall gives a 4 × 5 grid of 20 pieces. Turning the tile the other way gives 8 × 3, or 24 pieces. A setter may reuse some offcuts, so the true count usually falls between the area and grid figures.
The grid starts at a corner. Many setters center the layout instead so the cuts on opposite walls match, which can add a column or row. If you plan to center, check the floor area and allow for one extra row of cuts.
Who it is for and when to use it
Bathroom and kitchen renovations
Count floor, wall and backsplash tile for each surface and order whole boxes. A 10 ft × 18 in backsplash in 3 × 6 in subway tile needs 120 tiles, 132 with 10% waste.
Choosing a tile size
Compare how many pieces and cut edges different formats create in the same room before committing to a product.
Checking a quote or order
Confirm that a supplier's or installer's box count covers the room with a sensible allowance, and see the extra cost of pattern layouts.
Design and specification
Get a quick tile count for a room schedule or finish specification, with the inputs and method in the PDF or CSV.
Method, formulas & assumptions
Layout columns = ceil((room length + joint)/(tile length + joint)), with the same calculation for rows; 50% offset rows add one cut piece. Area estimate excludes grout; the cut list sizes the edge pieces. Grout = joint length per m² × joint × tile thickness × 1.6 kg/L; adhesive = area ÷ coverage per bag.
Imperial inputs are converted with exact factors (1 ft = 0.3048 m, 1 lb = 0.45359237 kg, 1 US gal = 3.785411784 L) before the calculation runs in SI, then results are converted back.
Common mistakes to avoid
- Buying large-format tile by area alone. Narrow edge strips use a full tile each, so the grid count can be well above the area estimate.
- Applying a straight-lay allowance to a diagonal or herringbone pattern.
- Ignoring tile orientation. Rotating a rectangular tile can change the number of cut pieces in a small room.
- Using the nominal tile size when the actual size on the box is smaller.
- Buying boxes from different lots. Check that shade and caliber codes on the boxes match before the job starts.
- Offsetting large rectangular tiles by 50%. ANSI A108.02 guidance limits the offset to 33% for tiles with any side longer than 18 in unless the manufacturer states otherwise, which also changes the cut pattern.
Scope & limits
Straight and offset grids start at a corner without offcut reuse; diagonal and herringbone use the area estimate, with the pattern's typical waste shown beside yours. Box count uses the larger area/layout allowance.
Frequently asked questions
How many 12x24 tiles do I need for 100 square feet?
You need 50 tiles of 12 × 24 in to cover 100 square feet, since each covers 2 square feet. With a 10% waste allowance, buy 55.
How many tiles do I need for a 10x10 room?
A 10 × 10 ft room is 100 square feet: 100 tiles of 12 × 12 in or 25 tiles of 24 × 24 in before waste. With 10% waste that is 110 or 28 tiles.
How much extra tile should I buy?
A common allowance is 10% for a straight layout, 15% for diagonal and 15 to 20% for herringbone. Allow more for small rooms with many cuts.
How do I calculate how many tiles I need?
Divide the room area by the area of one tile in the same units, then add a waste allowance and round up to whole boxes. For large tiles, also count the grid of columns and rows, because each cut edge piece uses a full tile.
Do grout lines reduce the number of tiles needed?
Slightly. A 1/8 in joint makes each 12 × 12 in tile cover about 2% more floor. The area estimate ignores this and stays conservative; the layout count includes the joint.
How many 600 x 600 tiles are in a square metre?
Each 600 × 600 mm tile covers 0.36 square metres, so one square metre needs 2.78 tiles before waste.
Does the calculator handle diagonal or herringbone layouts?
Partly. Choose the layout pattern: straight and 50% offset grids are counted piece by piece from one corner, while diagonal and herringbone use the area estimate. Each pattern shows the count at its typical waste (10%, 15% or 20%) beside the count from your own allowance. Draw a cutting plan for expensive tile.
Do I need an account to download the result?
No. All calculations, local file processing and exports on this page are free, without an account.
Where are my inputs stored?
The tool keeps inputs in this browser tab. It does not upload them or create a cloud copy. Save or download anything you want to keep before leaving the page. Standard site analytics may operate independently of the tool.
Can I work in metric instead of imperial?
Yes. Use the Imperial / Metric switch above the inputs. Imperial (feet, inches, pounds, gallons) is the default; switching converts every dimensional field and result, and your choice is remembered across the free tools in this browser.
Further reading
- Bathroom template
- Kitchen template
- Interior design projects in Harth
- All materials & quantities tools
- All free architecture & construction tools
- Harth resource library
In this category
Keep developing your project in Harth.
Bring your ideas, models and project research into one workspace. Downloaded results are yours to take with you.