How many tiles and boxes to buy
Tile quantity starts with area. Measure the floor or wall, divide by the area of one tile, add a waste allowance for cuts and breakage, then round up to whole tiles and whole boxes. For a 4 m × 3 m floor (12 m²) with 60 × 60 cm tiles, 10% waste and 4 tiles per box, you need 37 tiles, which means 10 boxes (40 tiles). At $72 a box that is $720.00. This is an area estimate for buying material, not a plan of where each tile and cut will go.
Area and unit conversion
Enter each rectangle in metres, centimetres, millimetres, feet or inches; every surface can use its own unit. Irregular rooms work best split into rectangles, and areas that will not be tiled, such as a built-in cabinet or a shower tray, can be subtracted. If you already know the total, enter it in m² or ft². Conversions are exact: 1 ft = 0.3048 m, 1 in = 2.54 cm and 1 ft² = 0.09290304 m², so 12 m² is 129.17 ft². The calculator does not know the shape of your room, so make sure exclusions sit inside the surfaces and do not overlap.
Waste before rounding
The waste allowance covers cut pieces, breakage and spares for later repairs. It is applied to the area first, and only then rounded to whole tiles. The order matters: 12 m² ÷ 0.36 m² is 33.333 tiles; with 10% waste the area becomes 13.2 m², or 36.667 tiles, rounded up to 37. Rounding first and then adding 10% would overstate the order. The 10% default is only an illustration. Diagonal layouts, herringbone patterns, large tiles and rooms with many corners usually need more; ask your supplier or installer. Tile installation guides such as this retailer’s guide describe the same method: split the area into rectangles, add waste, then round up to whole boxes.
Boxes versus loose tiles
Tiles are usually sold in boxes, so you often buy a few more than you need. In the example, 37 tiles need 10 boxes of 4, which hold 40 tiles: 3 extra tiles come only from rounding up to whole boxes. With no waste allowance the same floor needs 34 tiles, 9 boxes and costs $648.00. Keep a few spare tiles from the same batch; colours can differ between production runs.
Material cost from purchased boxes
The cost uses what you actually buy: whole boxes times the box price, purchased tiles times the tile price, or the nominal area in the purchased boxes times a price per m² or ft². It never charges for a fraction of a box. If several suppliers sell the same tile in different box sizes, compare their price per square metre with the unit price calculator. Contractors quoting a job can add their markup to the material cost with the margin and markup calculator.
What the estimate excludes
Results use nominal tile size and do not subtract grout joints, which makes the estimate slightly conservative. The tool does not plan a cutting layout, count cuts, estimate grout or adhesive, handle hexagons, mosaics or mixed tile sizes, or price labour, tax and delivery. Box coverage printed by the manufacturer may differ slightly from length × width × tiles per box.
FAQ
How many tiles do I need?
Divide the area to tile by the area of one tile, add your waste allowance, and round up. 12 m² of 60 × 60 cm tiles with 10% waste is 37 tiles.
How much waste should I enter?
It depends on the layout, tile size and room shape. 10% is a common starting point for straight layouts; patterns and diagonals often need more. Check with your installer.
Why do boxes add extra tiles?
Because you cannot buy part of a box. The tiles needed are rounded up to whole boxes, and the difference is shown separately from the waste.
Can I subtract doors and windows?
Yes. Add each area that will not be tiled as an exclusion. It must be inside a surface and must not overlap another exclusion.
Does this include grout gaps, cutting layout or labor?
No. It is an area-based material estimate. Grout gaps are not subtracted and grout, adhesive, cutting plans and labour are not included.
How do square feet convert to square metres?
Multiply square feet by 0.09290304 to get square metres, or divide square metres by 0.09290304 to get square feet.