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About this tool
Calculates how many tiles and boxes a floor or wall needs, plus the grout and adhesive quantities, counting the grout joint in the tile module.
A tile calculator converts a room or wall measurement into the number of tiles, the number of sealed boxes, and the grout and adhesive to buy with them. It counts the grout joint as part of each tile's covering module — (tile width + joint) × (tile height + joint) — which is why it gives a slightly lower tile count than a calculator that divides by the bare tile size. Grout uses the manufacturers' formula ((A + B) ÷ (A × B)) × joint × thickness × 1.6 kg per m², and adhesive the standard 1.5 kg per m² for every millimetre of bed depth.
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Under "The area", enter Length, "Width or wall height", Room units of Metres or Feet, and any "Area to deduct" for doorways, a shower tray or kitchen units.
Under "The tile", set Tile width, Tile height, "Grout joint (mm)", "Tile thickness (mm)" and "Wastage allowance (%)"; under Ordering, set Tiles per box, Price per box and the Notched trowel.
"Boxes to order" leads the result, with tiles with and without wastage, spare tiles, real wastage once boxed, "Covering module per tile", and Grout needed and Adhesive needed.
The grout gap is part of the covering module, so the count matches what is actually laid.
Real manufacturer formulas, not a flat guess, driven by tile size, joint width and trowel notch.
Rounds to sealed boxes and tells you the true wastage and the spares you will be left holding.
About 33 tiles bare, or 37 with a 10% wastage allowance. With a 3 mm grout joint each tile covers 603 × 603 mm = 0.3636 m², so 12 ÷ 0.3636 = 33.0 tiles. At four tiles per box that is 10 boxes, which delivers 40 tiles and leaves 6 spare.
For 600 × 600 mm tiles that are 9 mm thick with a 3 mm joint, about 0.14 kg per m². The formula is ((A + B) ÷ (A × B)) × joint width × tile thickness × 1.6, with every dimension in millimetres and 1.6 g/cm³ as the density of cementitious grout. Smaller tiles need far more — 100 mm mosaics use roughly six times as much.
Thin-bed adhesive is consumed at about 1.5 kg per m² for each millimetre of bed depth, and the trowel sets the depth: a 6 mm notch leaves roughly a 3 mm bed (4.5 kg/m²) and a 10 mm notch about 5 mm (7.5 kg/m²). A 12 m² floor with a 10 mm notch therefore takes about 90 kg — five 20 kg bags.
Around 5% for a straight grid in a rectangular room, 10% as a general default, and 15% or more for a 45-degree diagonal or a herringbone layout where every perimeter cut leaves an unusable offcut. Rounding up to sealed boxes usually pushes the delivered wastage higher still, which is shown separately here.
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