I am not a designer or color expert, but I would go with a light to medium gray. Never the whiter of your two colors. I would go grayer than the other color.

@Olychick thanks for your suggestion. I don't like grout as well, but this is the default option of my new townhouse builder which I cannot change. I think a light grey color would be better.

Are you saying you cannot choose any other grout colors but the two you posted?

@olychick No, I can choose grout colors, but cannot change the width of the grout lines. My builder said the lines will be as wide as the color sample, so I think the color of the grout would be so important and mismatched colors will make my tiles look ugly.

I would use a dark grout as close to the color of the tile as possible. What will look ugly is lots of grout lines that you will see with a too light grout. You want it to disappear. Unless you want it to look like this:

I to match grout so that blends.

I understand your concern,

having just chosen grout for our bathroom tile and wanting as little grout noticeable as possible. There are multiple grays in your tile and each tile is different. One tile looks quite light and another is darker. In your photo it looks like 3 grout choices. I agree with Nancy in Mich and would choose the medium or darker gray but NOT the light gray, which could create too much contrast and stick out and may show dirt and darken sooner.

Another vote to match it, you don’t want to see the grid lines. We have a somewhat similar tile in our kitchen and the grout we selected dried lighter than we thought and it was not pleasing to look at. Luckily we only tried in small area and quickly changed grout color.

@Jennifer Svensson@HU-229740923@eld6161@Nancy in Mich@OlychickThanks for your reply, I would find a medium or litter darker grey to match the tiles to minimize contrast.

Can you get some more samples in darker, grayer colors and post here?

eta: I just looked at your pics again and noticed (for the first time) that your first pic has grout samples alongside. I was just looking at your last pic with the two light samples! It seems the darkest (top) color is close, but a little warm for the cool grays in your tile. If you can find one not quite so warm, I think that could work.

@Olychick I just went to tile store to see grout samples and picked four colors which are Rolling Gray, Delorean Gray, Cape Gray and Platinum. I think Cape Gray and Platinum might be better. However, I've seen some negative review about Platinum saying it is white rather than gray. If that's the case, Cape Gray would be the winner.

Platinum looks too blue. Cape Gray looks like it will blend in nicely.

I agree with Cape Gray; that's the one I'd choose.