Tile Calculator — Tiles Needed & Cost

To calculate tiles needed, divide the total area to be tiled by the area of a single tile. Common UK tile sizes include 300 × 300 mm (0.09 m²), 600 × 300 mm (0.18 m²) and 600 × 600 mm (0.36 m²). Always add 10% for cuts and breakage, and increase that to 15% for diagonal layouts or complex patterns. A 4m × 3m bathroom floor is 12 m², so with 300×300mm tiles you need 12 ÷ 0.09 = 134 tiles, or 154 once 15% waste is added. Tile shops sell by the box, so check the coverage printed on it (typically 1–1.5 m²) and buy from the same production batch, because colour shading varies between batches. Look for the shade code on the box.

For wall tiling, measure each wall separately and subtract windows or other openings. For floor tiling, measure the room at its longest and widest points, including any alcoves. The calculator handles rectangular, L-shaped and irregular rooms by letting you split the area into sections. Enter your room dimensions, tile size and layout pattern, and it returns the number of tiles, the number of boxes and an estimated cost. It also estimates adhesive and grout: roughly 2–3 kg of adhesive per m² for wall tiles and 3–5 kg per m² for large floor tiles.

The tile type decides both the price and where you can use it. Ceramic is the cheapest at £15-£40/m², but it is softer and belongs on walls and light-traffic floors only. Porcelain is harder, denser and frost-proof at £25-£70/m², which suits heavy-traffic floors, outdoor areas and wet zones. Natural stone (marble, limestone, slate, travertine) costs £40-£120/m², needs sealing and can stain. Glass mosaic at £40-£200/m² is for feature walls and splashbacks, while unglazed quarry tile, the traditional UK farmhouse floor, runs £25-£60/m². Check the anti-slip R-value too: R9 is fine for an indoor wet area, R10-R11 for wet rooms and kitchens, and R12 or above is commercial and outdoor territory.

Your layout pattern changes the waste figure. A straight grid is the simplest and loses about 5-10%, a brick or offset pattern with tiles staggered by 50% loses 7-10%, and diagonal laying needs 15% but makes a room look larger. Herringbone also needs 15% and involves more complex cuts, while a Versailles multi-size pattern can waste up to 20% and is a professional job. Bookmatching, where marble veins are mirrored across adjacent tiles, gives a premium look but demands careful sequencing. Allow extra for cuts around the toilet, shower and doorways. Lay the pattern out dry before opening the adhesive, then start from the centre of the room and work outward so the cut tiles end up at the edges where they are least visible.

Adhesive and grout are the items most often left off the shopping list. Powdered adhesive comes in 20kg bags at £15-£25 each, and the type matters: standard adhesive for ceramic, flexible adhesive for porcelain on floors that move, rapid-set when time is short. Grout is sold in 5kg bags, each covering 5-15 m² depending on tile size and joint width, with typical joints of 2mm on walls, 3mm on floors and 5mm or more for rustic stone. Epoxy grout is waterproof and stain-resistant but costs 3-5× as much as cement grout, which still makes it worth considering for kitchens and bathrooms. Natural stone also needs sealer at £25-£60/litre, repeated every 1-3 years.

As a worked budget, a 12 m² bathroom floor in mid-range porcelain at £35/m² needs 14 m² once waste is included, so £490 in tiles, plus 4 bags of adhesive at £20 (£80), 2 bags of grout at £20 (£40) and around £40 for spacers, profiles and sealant, giving total materials of £650. Labour is the larger number: floor tiling costs £60-£90/m², and walls and complex patterns cost more. A 12 m² floor plus 30 m² of walls at £75/m² comes to £3,150 in labour, which is why a full mid-range bathroom re-tile typically lands at £3,500-£5,000. Doing it yourself saves £2,500-£4,000, but plan for 3-5 days of work and expect mistakes on a first attempt.