Tile calculator
Work out how many tiles, boxes, grout and adhesive you need for a floor, a bathroom wall or a splashback. Type your sizes and the answer changes as you go.
The short answer
Multiply length × width in metres for each area and add them up. Add 10% for cuts (15% for diagonal, 20% for herringbone). Divide by the m² in one box and round up to whole boxes.
Your tiles
6 boxes
22 tiles, 7.92 m² of tile for 7.2 m² of floor
- Area to tile
- 7.2 m²
- 3 × 2.4 m
- With 10% extra for cuts
- 7.92 m²
- 7.2 m² + 10% for a straight layout.
- Tiles
- 22
- Each 600 x 600 mm tile covers 0.3624 m² with its 2 mm joint. 7.92 ÷ 0.3624 = 21.9, rounded up.
- Boxes
- 6
- 22 tiles = 7.92 m² of tile. 7.92 ÷ 1.44 m² a box = 5.5, rounded up. That's 24 tiles.
- Grout
- 1.1 kg
- 0.15 kg a m² (ARDEX's formula for ARDEX FG 8, plus 15%) × 7.2 m². Buy 1 × 1.5 kg bag.
- Adhesive
- 21 kg
- A 20 kg bag of ARDEX X 18 covers about 7 m² of floor with a 10 mm notched trowel. 7.2 ÷ 7 × 20 kg = 21 kg. Buy 1 × 20 kg bag and 1 × 5 kg bag.
Large tiles often need a bigger trowel and adhesive on the back of each tile as well. That uses more adhesive, so ask your tiler before you buy.
An estimate to help you plan. Check your sizes on site, and buy every box in one order so the shade matches.
How to measure for tiles
Measure in metres
Measure each area at its widest points. Length × width gives the m². A floor 3.6 m long and 2.4 m wide is 3.6 × 2.4 = 8.64 m².
Split odd shapes
Split L-shaped rooms into rectangles. Measure each one and add them up. The calculator adds them for you.
Walls: width × height
Measure each wall's width and height. Take away windows, doors and anything you won't tile, like a bath or a vanity.
Splashbacks
Measure from the benchtop to the bottom of the cupboards, then the full length you're tiling.
Tile sizes at a glance
How much one tile covers, how many you need for each m² once a 2 mm grout joint is counted, and what a common box holds. Check your own box, as they vary.
| Tile (mm) | One tile (m²) | Tiles per m² | Common box (m²) | Tiles in it |
|---|---|---|---|---|
| 600 x 600 | 0.36 | 2.8 | 1.44 | 4 |
| 300 x 600 | 0.18 | 5.5 | 1.44 | 8 |
| 600 x 1200 | 0.72 | 1.4 | 1.44 | 2 |
| 450 x 450 | 0.2025 | 4.9 | 1.0125 | 5 |
| 75 x 300Subway | 0.0225 | 43 | 0.99 | 44 |
| 52 x 160Zellige look | 0.0083 | 114.3 | 1 | about 120 |
| 100 x 100 | 0.01 | 96.1 | 1 | 100 |
How the calculator works it out
Tiles
Each tile covers its own size plus its share of the grout joint. A 600 x 600 mm tile with a 2 mm joint covers 0.602 × 0.602 = 0.3624 m². We take your area, add the extra for cuts, divide by that and round up to whole tiles.
Extra for cuts
Tiles at the edges get cut, and some offcuts can't be used. Some tiles break, and it's worth keeping a few for repairs. How much extra you need depends on the layout:
| Layout | Extra | Why |
|---|---|---|
| Straight | 10% | Cuts only at the edges. |
| Brick bond | 10% | Each row starts with a part tile. The offcut often starts the next row. |
| Diagonal | 15% | Every edge tile is cut on an angle. |
| Herringbone | 20% | Lots of angled cuts at every edge. Tile shops quote 15% to 30%. |
Small areas like a splashback, and big tiles, waste more, because most tiles touch an edge. The drawing in the calculator shows your area with the tiles laid from the middle, and which ones the walls cut. Change the extra if your area is small or has lots of corners.
Boxes
Tiles are sold by the box. We turn your tiles into m² of tile, divide by the m² in one box and round up. A box of 600 x 600 tiles often holds 4 tiles, which is 1.44 m². Buy every box in one order, so the shade matches.
Grout
We use the formula ARDEX Australia's grout calculator uses for ARDEX FG 8, a cement grout for joints 1 to 8 mm wide:
(tile length + tile width) × joint depth × joint width ÷ (tile length × tile width) × 2.0 = kg per m²
All sizes are in mm, and the joint depth is the tile's thickness. Then we add 15% for waste, as ARDEX's calculator does. Small tiles have more joints, so they need much more grout:
| Tile | Joint | Grout a m² | 5 kg covers |
|---|---|---|---|
| 600 x 600 x 10 mm | 3 mm | 0.23 kg | 21.7 m² |
| 600 x 600 x 10 mm | 2 mm | 0.15 kg | 32.6 m² |
| 300 x 600 x 9 mm | 2 mm | 0.21 kg | 24.2 m² |
| 600 x 1200 x 10 mm | 2 mm | 0.12 kg | 43.5 m² |
| 75 x 300 x 7 mm | 2 mm | 0.54 kg | 9.3 m² |
| 52 x 160 x 8 mm | 2 mm | 0.94 kg | 5.3 m² |
| 100 x 100 x 8 mm | 2 mm | 0.74 kg | 6.8 m² |
ARDEX FG 8 comes in 1.5, 5 and 20 kg bags. Other grouts weigh more or less for the same joint, so check the bag of the one you buy.
Adhesive
ARDEX's data sheet for ARDEX X 18, a flexible wall and floor tile adhesive, says a 20 kg bag covers about 7 m² of floor with a 10 mm notched trowel, or about 11 m² of wall with a 6 mm notched trowel. We divide your area by that. It also comes in 5 kg bags, so small jobs don't need a whole 20 kg bag. Other adhesives cover more or less:
| Adhesive (20 kg bag) | Floor, 10 mm trowel | Wall, 6 mm trowel |
|---|---|---|
| ARDEX X 18 | about 7 m² | about 11 m² |
| ARDEX X 7 | about 7 m² | about 10 m² |
| ARDEX X 17 | about 6 m² | about 10 m² |
| ARDEX MPP | about 8 m² | about 12 m² |
| ARDEX Abaflex | about 5 m² | about 7 m² |
Coverage changes with the trowel, the tile and the surface. Large tiles often need a bigger trowel and adhesive on the back of each tile too, which uses more. If your bag gives a different figure, type it under “More options” in the calculator.
Your questions, answered
Tile calculator questions
What people ask Google most about tiles, grout and adhesive.
How do I work out how many tiles I need?
Measure the length and width of the area in metres and multiply them to get m². Add 10% for cuts, or more for diagonal and herringbone layouts. Divide by the area one tile covers, counting its grout joint, and round up. The calculator above does all of this for you.
How much extra tile should I buy?
Add about 10% for straight and brick bond layouts, 15% for diagonal and 20% for herringbone. Small areas like a splashback, and big tiles, waste more, because most tiles touch an edge and get cut. Keep a few spare tiles for repairs later.
How much area does a 600 x 600 tile cover?
One 600 x 600 mm tile covers 0.36 m². You need about 2.8 tiles for every m², or 2.76 with a 2 mm grout joint. A box of 4 tiles covers 1.44 m², a common box size for this tile.
What is the 3-4-5 rule for tiling?
It's a quick way to check a corner is square before you set out your tiles. From the corner, measure 3 units along one wall and 4 units along the other. If the distance between those two marks is exactly 5 units, the corner is square. In a small room, use 300, 400 and 500 mm.
How much grout do I need per m²?
It depends on the tile size, the joint width and the tile's thickness. Small tiles need much more, because they have more joints. Using ARDEX's figures for FG 8 grout, with 15% added for waste: 600 x 600 x 10 mm tiles with 3 mm joints need about 0.23 kg per m². 100 x 100 x 8 mm tiles with 2 mm joints need about 0.74 kg per m².
How much does a 5 kg bag of grout cover?
With ARDEX FG 8 and 15% for waste, 5 kg grouts about 21.7 m² of 600 x 600 x 10 mm tiles with 3 mm joints, or about 6.8 m² of 100 x 100 x 8 mm tiles with 2 mm joints. A 2.5 kg bag covers half that, and a 20 kg bag four times as much.
How many m² does a 20 kg bag of tile adhesive cover?
ARDEX's data sheets for 5 of its 20 kg adhesives give about 5 to 8 m² of floor with a 10 mm notched trowel, and 7 to 12 m² of wall with a 6 mm notched trowel. ARDEX X 18 covers about 7 m² of floor or 11 m² of wall. Check the bag you buy: coverage changes with the trowel, the tile and the surface.
How do I work out how much tile adhesive I need?
Divide the area you're tiling by the m² one bag covers, then round up. For a 9 m² floor with ARDEX X 18: 9 ÷ 7 = 1.3 bags of 20 kg, so buy 1 × 20 kg bag and 2 × 5 kg bags.
What size trowel do I use for tile adhesive?
It depends on the tile and the surface. ARDEX's coverage figures use a 6 mm notched trowel on walls and a 10 mm one on floors, and its data sheets point to the Australian Standard AS 3958 for the trowel to use with each tile size. Large tiles often need a bigger notch and adhesive on the back of the tile too.
Do grout lines change how many tiles I need?
Yes, for small tiles. The joint makes each tile cover a little more. With 52 x 160 mm tiles and a 2 mm joint you need about 5% fewer tiles than with no joint. With 600 x 600 mm tiles the difference is under 1%.
Should I buy all my tiles at once?
Yes. Tiles are made in batches, and the shade can change a little from one batch to the next. Buying every box in one order keeps them matching. Keep a few spare tiles too, in case one cracks later.
Where the figures come from
- ARDEX FG 8 grout calculator : the grout formula, and 2.0 for FG 8.
- ARDEX FG 8 technical data sheet, July 2026 : joint widths, bag sizes and its own coverage table.
- ARDEX X 18 technical data sheet : about 7 m² of floor and 11 m² of wall a 20 kg bag.
- ARDEX X 7 technical data sheet : about 7 m² of floor and 10 m² of wall a 20 kg bag.
- ARDEX X 17 technical data sheet : about 6 m² of floor and 10 m² of wall a 20 kg bag.
- ARDEX MPP technical data sheet : about 8 m² of floor and 12 m² of wall a 20 kg bag.
- ARDEX Abaflex technical data sheet : about 5 m² of floor and 7 m² of wall a 20 kg bag.
By Hybrid Floors Australia. Figures checked 23 October 2026. Box sizes and tile thicknesses are common ones: check your own tile's box or product page.
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