Tile calculator
Work out how many tiles and boxes you need for a wall or floor. Add each area to tile, take off anything you won't tile around, pick your tile size, grout gap and layout, and get the tiles, boxes, adhesive and grout to buy.
Areas to tile
Width × height (or length × width for a floor) in metres. Add a row for each wall or part of the room.
Cut-outs
Anything inside those areas you won't tile: a window, a door, the bath panel or a fitted unit.
Tiles
Adhesive and grout
Adhesive use depends on the trowel notch: roughly 3 to 4 kg/m² for wall tiles with a 6mm notch, 5 to 7 kg/m² for floor tiles with a 10 to 12mm notch. Check the bag for its own figures.
Updates as you type. Runs in your browser. Nothing you enter is stored or sent.
How this calculator works
- Area: it adds up width × height for every area and takes off the cut-outs. A 2.4 × 2.4m wall less a 0.9 × 1.0m window is 5.76 − 0.9 = 4.86m².
- Tiles: each tile covers its own size plus half the grout gap all round, so a 600 × 300mm tile with a 2mm gap covers 602 × 302mm, or 0.1818m². The area is divided by that and the waste added: 4.86 ÷ 0.1818 = 26.7 tiles, plus 10% = 29.4, so 30 tiles.
- Boxes: tiles ÷ tiles per box, rounded up.
- Adhesive: area × the coverage you enter, rounded up to whole bags.
- Grout: the usual industry formula, (tile length + width) ÷ (length × width) × thickness × gap × 1.6, all in millimetres, gives kilograms per square metre. Narrow gaps and big tiles need very little; small mosaics need much more.
How much waste to allow
| Layout | Waste |
|---|---|
| Straight (grid) | 10% |
| Brick or offset | 10 to 12% |
| Diagonal | 15% |
| Herringbone | 15 to 20% |
| Lots of corners, pipes or small areas | add 5% |
Picking a layout sets a typical waste figure, and you can change it. Large-format tiles (600mm and over) break less often but each cut wastes more, so keep at least 10%.
Tips
- Buy all the tiles at once and check every box has the same batch number (shade and calibre), as colour and size can vary slightly between batches.
- Keep a few spare tiles for future repairs. Discontinued tiles are hard to match.
- Set out before you fix. Start from the centre line or a key feature so cuts at both ends are equal and no row ends in a thin sliver, the same idea as the first-row rip in our laminate flooring calculator.
- Walls in wet areas such as showers need tanking first, and floors over timber need a suitable backer board and flexible adhesive.
- Doing the rest of the room? The paint calculator works out the litres and tins, and the wallpaper calculator the rolls.
Frequently asked questions
How many tiles do I need for 1m²?
Divide 1 by the area of one tile in square metres. With a 2mm gap that's about 5.5 tiles of 600 × 300mm, 11 of 300 × 300mm, about 48 of 200 × 100mm, and 2.8 of 600 × 600mm, before waste.
How much extra tile should I buy?
10% for a straight layout, 15% for diagonal and 15 to 20% for herringbone. Add more for rooms with lots of corners or pipes.
How much tile adhesive do I need?
Usually 3 to 4kg per square metre for wall tiles and 5 to 7kg for floor tiles, depending on the trowel notch and how flat the surface is. A 20kg bag does about 5m² of wall or 3m² of floor. The bag gives the maker's coverage.
How much grout do I need?
Not much: for 600 × 300mm tiles, 8mm thick with 2mm gaps, about 0.13kg per square metre. Small tiles and wider gaps need far more: 100 × 100mm tiles, 6mm thick with 3mm gaps, take nearly 0.6kg per square metre.
Should I take off windows and doors?
Yes, take off anything you won't tile. Keep small items like sockets in, as the waste covers them.
Does it save or send what I type?
No. Everything is worked out in your browser, and nothing is stored or sent anywhere.
Results are estimates to help you plan. Coverage depends on the tiles, the surface and how you lay them, so check the boxes and bags and follow the manufacturer's instructions for adhesive, grout and any tanking or backer boards.