Short answer: choose grout from a dried sample joint between two of your tiles, not from a chart. Cement grout is darker wet than dry, a chart is ink on card, and a screen is neither. How much the choice matters is set by joint length: at a 2 mm joint, grout is about 17.7% of a wall in 12.8 × 95 mm fingers, 3.3% in 75 × 300 mm subway tile and 0.7% in 600 × 600 mm. The product pages here record nothing about grout; this is the one decision the tile does not make for you.
| Format | Joint length per m² | Share of the surface that is grout at a 2 mm joint | At a 3 mm joint |
|---|---|---|---|
| Finger mosaic, 12.8 × 95 mm | 88.7 m | 17.7% | 26.6% |
| Strip mosaic, 20 × 145 mm | 56.9 m | 11.4% | 17.1% |
| Hexagon, 70 mm face | 28.6 m | 5.7% | 8.6% |
| Subway, 75 × 300 mm | 16.7 m | 3.3% | 5.0% |
| Subway, 100 × 300 mm | 13.3 m | 2.7% | 4.0% |
| 300 × 600 mm | 5.0 m | 1.0% | 1.5% |
| 600 × 600 mm | 3.3 m | 0.7% | 1.0% |
| 600 × 1200 mm | 2.5 m | 0.5% | 0.8% |
Joint width is set by the installer and is not recorded on any product page here; 2 mm and 3 mm are used only to turn a length into a share. Grout area is joint length × joint width.
1. Wet, dry and printed are three different colours
A cement-based grout is at its darkest when it is mixed and goes lighter as it cures, which is why a joint that looked right on the day reads pale a week later. The chart in the shop is printed ink on card under shop lighting. A photo on a screen is a third thing again. Only one of the three is the colour you will live with, and it is the one that has dried on your tile, in your room.
2. How much of the wall is grout
The table gives the share. On a 600 × 600 mm tile the grout is under one per cent of the surface, so a colour miss is a fine line. On a 12.8 × 95 mm finger mosaic it is closer to a fifth of the surface, so the grout is the second colour of the wall and a miss is a different wall. The same grout on those two formats is not the same decision; the joint length in the second column says how much is at stake.
3. Match, blend or contrast: what each one does
A grout close to the tile colour makes the field read as one surface and hides small set-out drift. A grout a step away, warm grey on white for instance, keeps the grid visible but quiet. A contrasting grout draws every joint as a line, so the layout becomes the pattern; it also shows every wandering joint. None of these is right; each is a choice about whether the eye should see tiles or a surface, and the dried sample tells you which one you have actually made.
4. The sample joint: two tiles, the real grout, dried
Ask the tiler to grout the joint between two of your tiles with the grout that will go on the wall, and to leave it to dry before you look. Look at it upright against the wall it is for, in daylight and again under the room's lights. One poster on an Australian renovation forum told the tiler in words that they did not want white, pointed at a colour on the chart, and got a floor whose joints dried white; the sample joint is how that conversation becomes a thing both people can see.
5. Write the name and code where the tiler will read it
Grout is sold by brand, range and a colour name or code, and two names in the same range can be a shade apart. Put the exact name and code on the order for the work, next to the tile, and keep the dried sample. Supplying your own tiles: what a tiling quote should list has the line for it.
6. Grout on a look tile
On a marble-look or terrazzo-look face the figure is in the tile, and a grout close to the ground colour lets the figure carry across the joints. A contrasting grout on a terrazzo look draws a 600 mm grid over the chips, so the wall reads as tiles first. Marble-look tiles: 14 faces compared and Terrazzo-look tiles: 5 faces compared list the grounds and figures on this site.
7. Grout on a mosaic sheet
A mosaic sheet arrives with its internal joints fixed by the mesh; the tiler sets only the joint between sheets, and it has to match the ones inside or the sheet edges draw a faint grid that grout will not hide. The grout colour then matters twice: for the joints inside the sheet and for whether the between-sheet joint disappears. Kit Kat tiles and Kitchen hexagon tiles give the sheet numbers.
8. What the product pages here record about grout
Nothing. No product page on this site records a joint width, a grout type or a grout colour, because those are decisions made on site by the installer with you. What the pages do record is the size that fixes the joint length, and that is the number that says how loud the grout will be.
Questions people ask
Does grout dry lighter or darker?
Cement-based grout usually dries lighter than it looks when wet; other grout types behave differently. The only reliable answer is a dried sample joint of the grout you will use.
Should grout match the tile or contrast with it?
Match to read a surface, contrast to read a grid. The more joint per square metre, the more the choice shows: 88.7 m for a finger mosaic against 3.3 m for a 600 mm square.
Can grout colour be changed after it has dried?
There are colourant products for that, and they are outside this guide. The simpler path is the dried sample joint before the wall is grouted.
Where these numbers come from
Joint lengths are calculated from the sizes recorded on the product pages on 5 September 2026: the tile's perimeter divided by twice its area, no joint. Grout share is joint length multiplied by an assumed width. Related: Subway tile layouts: 8 patterns, What a tiled surface asks you to clean and Small bathroom walls.