Tile Calculator

Measure your room, tell the calculator the size of the tile you have chosen, and it returns the number to order. Enter the room length and width in meters, the tile length and width in centimeters, and a waste allowance for the offcuts and breakages every job produces. The tile count and the floor area update as you type, so you can check them against a shop quote before you buy.

How the count is worked out

Divide the floor area by the area one tile covers and you get the number of tiles that would fit with nothing wasted. Multiply by the waste allowance and round up to a whole tile, since a box never holds a fraction of one.

tiles = ⌈ area ÷ tile area × (1 + waste ÷ 100) ⌉

The floor area is the room length times its width. The tile area is its length times its width, converted from centimeters to meters first, so a 60 cm side becomes 0.6 m. Getting both measurements into the same unit is the step people most often skip, and a tile quoted in centimeters cannot be divided into a room quoted in meters until both describe square meters. With the defaults — a 4.8 by 3.6 m room and 60 by 60 cm tiles at a 10% allowance — the floor area is 4.8 × 3.6 = 17.28 m². One tile covers 0.6 × 0.6 = 0.36 m², so 17.28 ÷ 0.36 = 48 tiles would cover the floor exactly. Adding 10% gives 52.8, and since you cannot order 0.8 of a tile it rounds up to 53. The upward rounding, shown as the ⌈ ⌉ ceiling brackets in the formula, is deliberate, because rounding down would leave a strip of bare floor with no tile to fill it.

From faience to porcelain

People have covered floors and walls with fired clay for more than five thousand years. The oldest securely dated tiles yet found come from Beret in Ethiopia, radiocarbon-dated to roughly 3550 BC, and fired clay was being shaped into flat facing slabs across Egypt and the ancient Near East through the third millennium BC. Egypt made the tile decorative as well as durable: the underground chambers beneath the Step Pyramid of Djoser at Saqqara, built around 2650 BC, and the south tomb of the same complex together held about 36,000 small blue-green faience tiles, set in bands that imitate hanging reed matting. The colour came from copper in the glaze, and the idea those tiles captured — a thin ceramic slab with a sealed, coloured face — has changed little since.

The most complete survival from the ancient world is the Ishtar Gate of Babylon, built around 575 BC under Nebuchadnezzar II, its walls of glazed brick carrying lions, bulls and dragons in relief against a deep lapis-blue ground. Glazed tilework later became a signature of Islamic architecture, and after the Muslim conquest of the Iberian Peninsula in the eighth century it took deep root in Spain and Portugal, where the tiles kept a name borrowed from Arabic: azulejo, from al-zulayj, meaning polished stone, rather than from the Spanish and Portuguese azul for blue, as is often assumed. The related Moroccan craft of cutting small glazed pieces into mosaic is called zellige. Tin-glazing, a white opaque coating that holds painted decoration, was developed in ninth-century Iraq and travelled west through Egypt, Persia and Spain. Italian workshops were producing tin-glazed earthenware from the later thirteenth century, and Italian maiolica reached its height in the fifteenth and sixteenth centuries. The technique moved north with the potters working in Antwerp by 1512, and the Delft potteries that flourished from about 1600 gave the blue-and-white Delft tile its name.

Medieval Europe also floored its churches and abbeys with encaustic tiles, whose pattern is inlaid in contrasting clay rather than painted or glazed on, so the design survives as the surface wears down. Making them by hand was slow, and tile stayed a luxury until industry changed the arithmetic. In 1840 the Birmingham engineer Richard Prosser patented dust-pressing, which compacts nearly dry powdered clay between steel dies. The patent was written for buttons, and it was the Staffordshire potter Herbert Minton, working it under licence, who turned it on tiles and found them quicker to make, uniform in size and far less likely to warp in the kiln. The architect Augustus Pugin designed encaustic floors that Minton produced for churches and for the rebuilt Palace of Westminster, where the pavements were laid from the 1840s onward. Flat, identical, affordable tiles poured out of the Victorian factories, and the same dust-pressing principle still shapes most of the ceramic and porcelain tiles laid today.

Why the waste allowance matters

No real floor is a whole number of tiles across. Every tile that meets a wall usually has to be cut, and the offcut is normally too small to use elsewhere, so it counts as waste. Ten percent is the usual starting point for a straight grid layout in a plain rectangular room. Raise it to 15% for a diagonal or herringbone pattern, where every wall produces a triangular cut, and toward 20% for rooms full of alcoves, pipe boxings or very large-format tiles, which yield fewer usable offcuts. Tiles also crack while being cut, and the odd one arrives from the factory already chipped, so the allowance covers breakage as much as offcuts.

Measuring and the grout question

Two practical points sit behind the numbers. Measure the room at floor level and to its widest points, because a bay, a chimney breast or an out-of-square wall changes the count more than most people expect. If a room is stepped or L-shaped, split it into rectangles, work each one out and add the results. This calculator also ignores grout joints, and it is right to: a 3 mm joint turns a 60 cm tile into a 60.3 cm module, which raises the area each tile covers by almost exactly one percent, and a 2 mm joint by under seven tenths of one percent. Both are far less than the waste allowance already absorbs, so counting each tile at its nominal size stays simpler and errs on the safe side. The figure worth checking on the box is coverage per square meter — a 60×60 tile gives 2.78 tiles per square meter, a 30×30 gives 11.1 — since comparing it against your floor area is a quick sanity check on the count returned here.

Buy by the count, keep some spares

Tiles are sold by the box, and coverage per box is not standardised. One 60 cm range might pack four tiles into a 1.44 m² box while another packs three. Work in tile count, as this tool does, then divide by the tiles-per-box figure printed on your chosen product and round up to whole boxes. Set aside five to ten spare tiles from the same batch once the job is done. Dye lots drift between production runs, so a replacement bought a year later rarely matches the original colour, while a spare from the batch you laid always does.

Tile sizes around the world

Metric markets — the UK, most of Europe and Australia — sell tiles in centimeters, with 30×30, 45×45, 60×60 and large 60×120 the common sizes. The United States sells in inches, where 12×12, 18×18 and 24×24 inch tiles come close to 30, 45 and 60 cm without matching them exactly: an inch is defined as exactly 2.54 cm, so those three sizes are 30.48, 45.72 and 60.96 cm. Canadian suppliers routinely quote both. If your tile is given in inches, multiply by 2.54 to get centimeters before entering it, and use the converted figure rather than the round number the box advertises. Wherever you are, order the whole floor in one batch so every tile comes from the same dye lot, and measure the room itself rather than trusting a plan, since walls are rarely as square or as straight as a drawing makes them look.

Frequently asked questions

How many 60x60 tiles do I need for a room?

Divide the floor area in square meters by 0.36, the area one 60 cm tile covers, then add a waste allowance and round up. A 17.28 m² room needs 48 bare tiles, or 53 once a 10% allowance is added. For a room half that size, the tile count roughly halves too.

How much extra tile should I buy for waste?

Allow 10% over the bare coverage for a straight grid layout in a plain rectangular room, 15% for diagonal or herringbone patterns because every wall produces a triangular cut, and up to 20% for rooms with many corners, alcoves or large-format tiles. The offcut from a cut edge is usually unusable, and a few tiles crack while being cut.

How do I convert a tile size from inches to centimeters?

Multiply the inch figure by 2.54. A 12 inch tile is 30.48 cm, an 18 inch tile is 45.72 cm and a 24 inch tile is 60.96 cm. Enter the centimeter figure in the tile length and width fields, or measure one tile with a tape.

Why buy tiles by the count rather than by area?

Boxes are not standardised, so two different 60×60 cm ranges can pack a different number of tiles per box and cover a different area. Work out the tile count first, then divide by the tiles-per-box figure printed on your chosen product and round up to whole boxes. That is what keeps you from ending up one tile short.

Should I keep spare tiles after tiling?

Yes, set aside five to ten spare tiles from the same batch. Dye lots shift between production runs, so a tile bought a year later to replace a cracked one rarely matches the original color exactly. A spare from the batch you laid is the only reliable match.