How much tile do I need?

Tile is sold by the square metre, the tile or the box. The quantity you need starts as an area. For a rectangular floor, length times width is the area. A room 3.2 metres by 2.4 metres is 7.68 square metres. This guide does not turn that into a price.

Add wastage before you order

Cuts along the edges, and the odd broken tile, mean you need more than the bare area. Ten percent is a common allowance for a straight grid: 7.68 square metres becomes about 8.45 square metres. A diagonal layout, a bay window, a step or several doorways needs more than ten percent. If you are unsure, measure those extra strips and add them, rather than hoping the offcuts will do.

Walls are separate rectangles. A splashback behind a worktop is not the kitchen floor, and a shower wall is not the bathroom floor. Add each rectangle, then add wastage to the total you will buy in that tile. Different tiles for the floor and the wall are two orders.

Boxes do not match the area exactly

The calculator stops at square metres. A box might cover 1.44 square metres, or some other figure printed by the retailer. Divide the order quantity by that coverage and round up to a whole box. A half box still has to be bought as a box. Mosaics on a mesh are often sold by the sheet, so use the sheet coverage the shop prints.

End-of-line and clearance ranges are a poor place to under-order. The same shade may not come back. Buy the full quantity, including wastage, in one go. End-of-line tiles and tile clearance are listed separately. Current sale prices per square metre are on tile prices per m².

What this sum leaves out

Adhesive, grout, trim and delivery are not part of the tile area. A large tile wastes more on a narrow cut than a small one. The retailer page is where box coverage, the unit and any minimum order are stated. If the price is tagged ex VAT, the square-metre figure excludes VAT as well.