Tile Calculator
Work out how many tiles and boxes you need for a floor or wall, including grout lines, a waste allowance for your layout, and the total cost.
Comment utiliser cette calculatrice
- 1Measure the length and width of the area you are tiling, in feet.
- 2Enter the tile dimensions in inches, exactly as printed on the box.
- 3Set your grout line width — 1/8 inch is standard for rectified floor tile.
- 4Choose your layout pattern so the right waste allowance is applied.
- 5Add the tiles-per-box and price figures from the product listing for a cost estimate.
Comment ça marche
Tile quantity formula
area = length × width − deductions tile coverage = (tile length + grout) × (tile width + grout) ÷ 144 tiles = area ÷ tile coverage tiles to buy = tiles × (1 + waste rate), rounded up boxes = tiles to buy ÷ tiles per box, rounded up
Each tile effectively occupies its own footprint plus half a grout line on every edge, which is why the grout width is added once to each dimension. Dividing by 144 converts square inches to square feet. The waste rate covers cut tiles at the edges, breakages, and the offcuts a diagonal or herringbone layout inevitably produces.
Exemple détaillé
A 12 ft × 10 ft floor is 120 sq ft. With 12 in × 24 in tiles and 1/8 in grout lines, each tile covers 2.02 sq ft, so 60 tiles cover the area exactly. A straight layout adds 10% waste, giving 66 tiles — 11 boxes of 6.
Tile Calculator : le guide complet
How much waste to allow
Waste is not optional. Every edge tile gets cut, every cut leaves an offcut that is usually unusable, and a small number of tiles arrive or end up damaged. A straight layout in a simple rectangular room needs about 10%; add a couple of points for a room with alcoves, doorways, or angled walls.
Pattern drives the rest. Running bond wastes a little more because alternate rows start with a half tile. Diagonal layouts cut every perimeter tile at 45°, which is why 15% is the usual figure. Herringbone and chevron waste the most — every tile at the boundary is cut, and 20% is a realistic minimum.
Large-format tiles also push waste up, because a single cut ruins a bigger piece. For tiles over 24 inches on a side, adding a few extra points on top of the pattern allowance is cheap insurance.
Why dye lots matter
Ceramic and porcelain tiles are manufactured in batches, and colour, shade, and even dimensions vary slightly from one batch to the next. The batch number is printed on the box as a shade or calibre code.
Running short mid-job and buying a second batch is the classic way to end up with a visible line across a floor. Order all the tile at once from the same batch, and keep the leftover box — a cracked tile three years later is easy to replace only if you have the original batch on hand.
Adhesive, grout, and the rest of the order
Thin-set adhesive coverage depends on the trowel notch, which in turn depends on tile size. A 1/4 in square-notch trowel covers roughly 85–95 sq ft per 50 lb bag; large-format tile needs a 1/2 in notch and covers closer to 40–50 sq ft per bag. Check the bag, because the range is wide.
Grout usage depends on tile size, grout width, and tile thickness — wider joints and smaller tiles both use more. As a rough guide, a 25 lb bag of sanded grout covers 100–200 sq ft of 12 × 24 tile at 1/8 in joints. Add spacers, a bag of levelling clips for large format, and edge trim for any exposed tile edge.
Questions fréquentes
How many tiles do I need for a 12x12 room?
A 12 ft × 12 ft room is 144 sq ft. With 12 in × 12 in tiles at 1 sq ft each, that is 144 tiles for exact coverage, plus 10% waste for a straight layout — about 159 tiles. Enter your actual tile size above, since coverage changes significantly with tile dimensions and grout width.
Should I include the grout lines?
Yes, and this calculator does. Ignoring grout lines slightly overestimates the number of tiles needed, because each tile plus its share of the joints covers more floor than the tile face alone. The effect is small with 1/8 in joints and mosaic-sized tiles, but it grows with wider joints.
How much extra tile should I buy?
The waste allowance is built in based on your pattern — 10% for straight, up to 20% for herringbone. Beyond that, keep one full spare box after the job for future repairs, since matching the dye lot later is usually impossible.
Do I measure the floor or the tiles first?
The floor. Measure the longest length and width, deduct anything not being tiled, then choose the tile size. Working the other way around tempts you to fit the room to the tile, which is how odd sliver cuts appear at the most visible wall.