Tiling
Grout Joint Width Changes How Many Tiles You Need
Tile quantity is calculated on tile size plus joint, not tile size — a detail that quietly changes the order on any large floor.
The repeating unit in a tiled floor is the tile plus one joint. A 300 mm tile with a 3 mm joint repeats every 303 mm. Over a 6-metre run that is nearly 20 tiles rather than 20, and across both axes the difference compounds. On small rooms it disappears into your waste allowance; on open-plan floors it does not.
Grout volume moves far more dramatically, because it scales with joint width and depth together. Doubling the joint from 1.5 mm to 3 mm roughly doubles grout consumption. Always compute grout from the actual joint you intend to lay, not the default on the bag.
Put this into practice
- Tile and Grout CalculatorHow many tiles, and how much adhesive and grout?
More facts like this
- Large Tiles Need a Flatter Floor Than Small OnesA large-format tile cannot flex over a hump. Anything over 400 mm needs the substrate flat to about 3 mm over 3 m, or the edges stand proud.
- Grout Cracks at Corners Because It's Rigid on Purpose — Caulk Isn'tGrouting a tub-to-tile corner instead of caulking it guarantees a crack within a season or two, no matter how carefully it's applied.
- Grout Sealer Wears Off Long Before It Looks Like It HasShower grout sealed once at installation and never again is typically unprotected within a year, well before it shows visible staining.