Tile Calculator — Tiles & Boxes Needed
Work out how many tiles and boxes you need, and what they cost, for a floor or wall from its area or length and width, the tile size and a waste allowance.
Example: a 120 ft² floor with 12 × 12 in tiles (1 ft² each) needs 120 tiles before waste — the area is in ft², the tile sides in inches.
Floor area: 120 ft² · One tile: 1 ft²
🔒 Calculated in your browser. Includes a waste allowance for cuts and breakage — increase it for diagonal or patterned layouts.
Tiles and boxes to buy
Enter the area to cover — or set "Enter the floor as" to "Length and width" and give the room's two sides — and the size of one tile, and the tool divides them to get the tile count, adds a waste allowance for cuts and breakage, and works out how many boxes you need. Tile size is entered in inches, centimetres or millimetres, whichever "Tile size in" says: it starts on inches for imperial and centimetres for metric, and a room in ft² can take a tile in mm. Type a price per tile, per box or per ft² or m² and the total cost is shown too. The line under it is plain about what that cost leaves out: adhesive or mortar, grout, spacers, backer board and trim are extra. A "Common tile size" select fills both sides with a stock size, in inches or millimetres as boxes are labelled either side of the Atlantic, and shows "Your own size" for anything else; a line under the counts reads back the floor area and one tile's area in the floor's own unit, the two figures the count is built from.
Allow for waste
A 10% waste allowance is a common default for straight layouts; increase it for diagonal or patterned installs, which waste more on cuts. Buying a full extra box also gives you spares for future repairs. Everything runs in your browser.
Why the waste percentage is not padding
Every cut tile leaves an offcut, and most offcuts are unusable. A plain grid on a square room wastes least; a diagonal or herringbone layout cuts every tile at the edge and wastes most; a room with alcoves, a chimney breast or a curved threshold wastes more again. Trade practice is around 10% for a straight layout in a simple room, and 15% or more for diagonal work or an awkward shape. Large-format tiles waste more than small ones, because each ruined cut costs more area. The default here is a starting point, not a recommendation for your room.
Grout lines, boxes and the spare box
The tile size you enter is the tile, not the tile plus its grout line. On a 300 mm tile a 3 mm joint adds about 2% to the coverage, which is inside the waste allowance and is why this is not worth modelling separately. Boxes are rounded up, so a leftover part-box is normal and expected. Keep it: tiles are made in batches and the shade drifts between them, so a box bought a year later to replace a cracked tile is often visibly not the same colour.
Frequently asked questions
How many tiles do I need?
Divide the area to cover by the area of one tile, then add ~10% for cuts and breakage. The tool does this and rounds up to whole tiles and boxes.
How much waste should I add?
Around 10% for a straight layout in a simple rectangular room, 15% or more for diagonal or herringbone patterns, and more again for a room with many corners, alcoves or curves. Large tiles waste more than small ones.
Does it allow for grout lines?
Not separately. A normal joint adds a couple of percent to the coverage, which sits comfortably inside any sensible waste allowance.
Why is the box count rounded up?
Because tiles are sold by the box. The remainder is the spare stock you want anyway — replacement tiles bought later frequently come from a different batch and a different shade.
Can it work out what the tiles will cost?
Yes. Type a "Price (optional)" and choose whether it is per tile, per box or per ft² (per m² in metric); the total cost appears as a third figure and joins the copied result. A price per area is charged on the tiles you buy, waste included, not on the bare floor. Nothing about cost appears until a price is typed, and the "Currency" select sets the money it is written in.
Do I have to type the tile size?
No. "Common tile size" lists stock sizes in inches and in millimetres, the way boxes are labelled on each side of the Atlantic; picking one fills both sides and the tile unit, and a size you type yourself shows as "Your own size".
Does the cost include adhesive and grout?
No, and the page says so. Once a price is typed, a line under the total reads “The cost is for the tiles alone — adhesive or mortar, grout, spacers, backer board and trim are extra.” Price those separately; what this page works out is the tiles and boxes and what they cost.