Whites are hard. All whites have undertones, so one white can bring out the undertones in another white or off-white, making it look dingy, yellow, or - heaven forbid - pink. Light is another factor - light bouncing off trees outside can make white cabinetry take on a green tone, and the color on the paint on the walls will reflects as well. Additionally, some lightbulbs cast a blue light, some cast yellow. It's enough to make you crazy :)

So, this is something you need to mock up to see if the two whites look good together. Make a sample board with the tile and grout, of a size that will fit under your cabinets, so you can place it and observe it throughout the day. Then, move it to a different spot and observe another day. I'd make your sample board at least 18" wide. If you're happy, then move forward with the project. I'd wait until your counters are in, if they aren't already - and if possible, paint too.

If the whites aren't playing nicely, you can post a picture here for suggestions on how to make it work - new lightbulbs, repaint walls a certain color, etc.

According to oldbat2be, you can make a sample board by using double sided tape to stick tile to board, then grout. You can also chip out the tiles and reuse them when you're done.

I agree, tape some tiles onto a board and test it out. I am not convinced of the benefit of grouting it before hand, but I am not among the experts here.

You just cannot tell until the two are up next to each other, so try it out!

I did this. My cabinets are Benjamin Moore White Wisp, which is not a pure white. It tends toward the gray (as opposed to the cream). We used some really white-white subway tile on the backsplash and I was petrified it would make my cabs look bad, but itâÂÂs totally fine. I actually also have white quartz counters, a white sink, and a white fridge. I canâÂÂt begin to tell you how nervous I was to have all these slightly different whites together but they all play very well together.