Tile Trim Calculator — Pieces, Corners & Joiners

Choose a trim one size up from your tile thickness — roughly 1–1.5mm larger for walls, 1.5–2mm for floors — so the trim's leg clears the tile plus the adhesive bed beneath it. For an 8mm tile use a 10mm trim, and for a 10mm tile step up to the next size your chosen range offers. The exact increment varies by manufacturer: the Genesis ESA aluminium range runs 2.25/3.25/4.25/6/8/10/12/15mm (so a 10mm tile takes the 12mm size), while Schluter SCHIENE offers a 12.5mm size. A trim the same depth as the tile leaves the tile face sitting proud of the trim once the adhesive is added. If your tiles vary in thickness (handmade or natural stone), size against the thickest tile. Most UK tiles are 8–12mm thick.

Tile trim is needed on any exposed tile edge — where tiles end at a wall corner, window reveal, shelf edge, or where tiling finishes partway along a wall. External corners (outward-facing) are the most common location. Internal corners (inward-facing) can use trim but are often just grouted. Tile trim is not needed where tiles meet the ceiling or floor as these joints are usually sealed with silicone.

Round edge (also called 'bullnose') is the most popular — it provides a smooth curved edge. Square edge gives a modern, clean-lined look. L-shape provides a right-angle finish for window reveals. Box section creates a raised border effect. Step edge is used for transitions between different floor levels. Chrome, brushed steel, and white are the most popular finishes.

Tile trim joiners (connectors) create a neat junction between two lengths of trim. They're essential — butting two pieces together without a joiner looks untidy and can separate over time. Internal and external corner pieces are pre-formed 90° turns that give a professional finish. All joiners and corners should match the trim profile and finish.

Yes — alternatives to tile trim include: mitring tile edges at 45° for external corners (requires skill and a wet saw), using bullnose tiles (with a factory-finished rounded edge), or simply grouting exposed edges. Mitring gives the most seamless look but is time-consuming and fragile on thin tiles. For DIY, trim is easier and more forgiving.