How many tiles do I need? How to use the tile calculator
- 1Choose the job: a floor, a floor with tile skirting, a bathroom or kitchen (floor and walls), or walls only.
- 2Measure the room's length and width, or enter the area, and take off anything that won't be tiled, such as a shower tray.
- 3Pick a common tile size (such as 600 × 600 mm, sold as 2 × 2 ft) or type your own, then the joint width and the layout. The spare fills in by itself; change it if your tiler recommends another figure.
- 4For skirting, enter its height. For walls, choose how high to tile and check the doors and windows.
- 5Add the tiles per box — or the area per box, if that is what the box shows — to see how many boxes to buy. Add the shop's price per box, per m² or ft², or per tile for the cost.
How to calculate tiles (formula)
- 01Area to tile = length × width − area not tiled
- 02Space one tile takes = (tile length + joint) × (tile width + joint)
- 03Tiles = area to tile ÷ space one tile takes
- 04Tiles to buy = tiles × (1 + spare %), rounded up
- 05Boxes = tiles to buy ÷ tiles per box, rounded up
- 06Skirting strips = (perimeter − doorways) × (1 + spare %) ÷ tile length; strips per tile = tile width ÷ (skirting height + 3 mm saw cut), rounded down
- 07Wall area = length of wall × tiled height − doors − windows − areas not tiled
- 08Boxes by area = tiles to buy ÷ tiles in one box, rounded up; tiles in one box = area per box ÷ tile area, rounded down
- 09Cost = boxes × price per box, or area of those boxes × price per m² (ft²), or tiles × price per tile
- 10Adhesive ≈ area × rate for the tile size (2–8.5 kg/m²) × 1.1 · Grout ≈ area × ((L + W) ÷ (L × W)) × tile thickness × joint × 1.6 kg/L × 1.1
Each tile takes up its own size plus half a joint on every side, which is why the joint is added to the tile size. Wide joints on small tiles make a real difference.
The spare covers cut tiles along the edges and the odd breakage. Straight and brick layouts usually need about 10 %; diagonal layouts create more cuts, so 15 % is common, and herringbone about 20 %. Small rooms with many corners may need more.
Tile skirting is usually cut from the floor tiles: a 600 mm (24 in) tile gives 5 strips of 100 mm (4 in), each as long as the tile. Six strips would need exactly 600 mm with nothing left for the saw cuts, so we allow 3 mm per cut.
Many boxes, especially in Pakistan, India and the US, show the area they cover instead of (or as well as) the number of tiles: 4 tiles of 600 × 600 mm are 1.44 m² (15.5 ft²). The calculator turns that area back into whole tiles, so a rounded figure on the box can never leave you a tile short.
The adhesive and grout under the results are a first idea of what to buy with the tiles. Adhesive uses the trowel-notch rates of our tile adhesive calculator for your tile size — 3.1 kg/m² for tiles up to 300 mm (12 in), 5 kg/m² for floor tiles up to 450 mm (18 in) and 8.5 kg/m² for larger tiles, which are back-buttered too. Grout uses the grout calculator's joint-volume formula with a tile 8 mm thick (10 mm for tiles over 300 mm).
Tile calculation example
A 3 m × 2 m floor is 6 m².
With 300 mm × 300 mm tiles and 3 mm joints you need 65.4 tiles before spares.
Adding 10% for cuts gives 72 tiles, which is 7 boxes of 11.
Tiles per square metre and spare by layout
| Tile size | Per m², no joint | Per m², 3 mm / ⅛ in joint | Per 100 ft², no joint | Per 100 ft², 3 mm / ⅛ in joint |
|---|---|---|---|---|
| 100 × 100 mm | 100 | 94.26 | 929 | 875.7 |
| 200 × 200 mm | 25 | 24.27 | 232.3 | 225.4 |
| 300 × 300 mm | 11.11 | 10.89 | 103.2 | 101.2 |
| 300 × 600 mm (“1 × 2 ft”) | 5.56 | 5.47 | 51.6 | 50.8 |
| 400 × 400 mm | 6.25 | 6.16 | 58.1 | 57.2 |
| 600 × 600 mm (“2 × 2 ft”) | 2.78 | 2.75 | 25.8 | 25.6 |
| 600 × 1200 mm (“2 × 4 ft”) | 1.39 | 1.38 | 12.9 | 12.8 |
| 800 × 800 mm | 1.56 | 1.55 | 14.5 | 14.4 |
| 12 × 12 in | 10.76 | 10.54 | 100 | 97.9 |
| 12 × 24 in | 5.38 | 5.3 | 50 | 49.2 |
| 16 × 16 in | 6.05 | 5.96 | 56.3 | 55.4 |
| 24 × 24 in | 2.69 | 2.66 | 25 | 24.7 |
| 24 × 48 in | 1.35 | 1.34 | 12.5 | 12.4 |
Whole tiles before any spare, worked out with this calculator's formula. The joint is 3 mm for metric sizes and ⅛ in (3.2 mm) for inch sizes. In Pakistan and India, 300 × 600, 600 × 600 and 600 × 1200 mm tiles are sold as 1 × 2, 2 × 2 and 2 × 4 ft, but they are slightly smaller than the name (600 mm is 23.6 in), so use the mm size.
| Layout | Spare to add | Tiles to buy for 10 m² of 300 × 600 mm tiles | Tiles to buy for 100 ft² of 12 × 24 in tiles |
|---|---|---|---|
| Straight (grid) | 10% | 61 | 55 |
| Brick / offset | 10% | 61 | 55 |
| Diagonal (45°) | 15% | 63 | 57 |
| Herringbone | 20% | 66 | 60 |
The spare this calculator fills in for each layout, with 3 mm joints for the metric tiles and ⅛ in joints for the inch tiles. Small rooms with many corners may need more.
Tips before you buy
- Check that every box has the same batch or shade code — tiles from different batches can look slightly different.
- Keep at least one spare box after the job so you can replace a cracked tile later.
- Large-format tiles (60 cm and above) are heavy and need a flat floor; ask about levelling before you buy.
- Want to see the layout first? Try the tile visualizer to count whole and cut tiles for your exact room.
Frequently asked questions
How much extra tile should I buy?
About 10 % for straight or brick layouts, 15 % for diagonal and about 20 % for herringbone. Add more for small rooms with lots of corners, or if the tiles are fragile.
How many skirting strips do I get from one tile?
A 600 mm (24 in) tile gives 5 strips of 100 mm (4 in) once you allow for the saw cuts, so a 600 × 600 tile makes about 3 m (10 ft) of skirting. The calculator works this out for your tile and skirting height.
How high should bathroom wall tiles go?
In Pakistan and India 7 ft (2.1 m) or full height is usual. In the UK and Europe many bathrooms are tiled to half height (1.2 m), with full height around the shower. A kitchen splashback is about 0.45–0.6 m (18–24 in).
Does the grout joint change how many tiles I need?
Yes. Each tile covers its own size plus the joint, so wider joints mean slightly fewer tiles. With small mosaic tiles the difference is significant.
How do I measure an L-shaped room?
Split it into rectangles, work out each area, and add them up. Our square footage calculator does this for you; enter the total here using the "Enter the area" option.
How many tiles are in a box?
It depends on the tile and the maker, so read the label. Boxes are sold by the number of pieces, and the label usually also gives the area they cover: pieces × tile length × tile width. For example, Kajaria packs its 600 × 600 mm tiles 4 to a box, which is 4 × 0.36 m² = 1.44 m² (15.5 ft²). Enter the pieces per box in “Tiles per box” and the calculator rounds up to whole boxes.
Should I round up to whole boxes?
Yes. Tiles are usually sold by the box, so the calculator always rounds up. Leftover tiles are useful for future repairs.
My box only shows square metres or square feet. How many boxes do I need?
Choose "By the area on the box" and type the area printed on it. Boxes = tiles to buy × tile area ÷ area per box, rounded up: 72 tiles of 600 × 600 mm are 25.92 m², so boxes of 1.44 m² (4 tiles) make 18 boxes.
How much tile adhesive and grout do I need?
Roughly 3–5 kg of cement-based tile adhesive per m² for tiles up to 450 mm (18 in) and about 8.5 kg/m² for large tiles that are also back-buttered, plus 0.1–0.3 kg of grout per m² for 2–3 mm joints. The results show both for your job; the tile adhesive and grout calculators give exact figures for your trowel, tile thickness and bag size.
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Sources
- Formula: standard tile coverage method (tile + joint footprint). Waste allowances: common trade guidance.
- Tiles per box, example: Kajaria 600 × 600 mm vitrified tiles, 4 pieces (1.44 m²) per box, as listed by Kajaria dealers.
- Adhesive rates by trowel notch: LATICRETE 254 Platinum data sheet (coverage per 50 lb bag), as used by our tile adhesive calculator
- Tile thickness for the grout estimate: Keope tile thickness guide (9 mm is the usual indoor floor tile, 6 mm on walls)
Formulas last reviewed: September 30, 2026 ·How we check our formulas