Splashback Tile Calculator: Tiles, Boxes and Grout

Most tile calculators divide your wall area by the size of a tile, which undercounts on a splashback. A splashback is a narrow strip, so a cut tile sits at the end of almost every row and at the top of every column, and each of those cuts uses up a whole tile. This calculator lays your tiles out row by row the way a tiler would, counts every cut piece as a full tile, then adds your spare allowance and rounds up to whole boxes. Measure each section separately, for example the strip behind the sink, the panel behind the range cooker and the run either side of a window.

How the count works

For each section the calculator works out how many rows of tiles reach from the worktop to the top edge, and how many tiles fill each row, allowing for the grout joint between them. Any part tile at the end of a row or along the top is counted as a whole one, because you cannot buy part of a tile and an offcut from one row is rarely the right size for another. In brick bond, every other row is shifted by half a tile, so those rows start and finish with a cut and usually need one extra tile.

The grout figure uses the coverage formula many grout makers publish: tile length plus width, divided by length times width, multiplied by the joint width, the joint depth (taken as the tile thickness) and 1.6. Check the coverage on your chosen bag, as some epoxy and rapid-set grouts differ.

Measuring tips

• Measure height from the top of the worktop, not the floor, and up to the underside of the wall units or the height you want to stop at.
• Behind a range cooker, tile the full width of the cooker and up to the hood or the canopy. Check your cooker's manual for any heat clearance it asks for.
• Do not subtract sockets and switches: you tile round them, and the cut tiles they create are already covered by the cuts allowance.
• If you are choosing between sizes, try two or three in the calculator. Larger tiles mean fewer joints but more waste on a short splashback, because a 600 x 300 mm tile laid flat on a 45 cm high strip gives one full row and a row of cuts.