I’m on the east coast which means slabs are 3 cm or almost 1 1/2”. The standard 34 1/2” install height has been fine for every kitchen I’ve installed including my last house which was ikea with marble

oh good to know, thank you!

We had an Ikea kitchen installed last year and the contractor built solid bases for the cabinets to sit on rather than using the adjustable Ikea legs. It feels like a much more solid platform for the countertop to sit on which might be a consideration for real stone. Edited to add that with a custom base, you can make the height whatever you want, ditto for the toe kick.

Custom base is fine but it’s no more solid than hanging from the steel support rail ikea designs with their adjustable feet. Their legs also have an inch or more of adjustability so you can get any height with their legs. When you get the toe kick over a certain height you will need to get a new toe kick material as the ikea kick only comes one size. I promise I’ve installed dozens of Ikea kitchens with their standard legs with stone tops.

This is a complete non issue. Unless you have cabinets designed to sit on the counter. Which Ikea does poorly, as they do not have anything that aligns with the standard 18"H space between counters and uppers, and have it work with a standard US 96" ceiling. 20" is too tall, and 15" is too low.

Thank you all! DeWayne, I actually DO have a cabinet designed to sit on the countertop, which is why I'm fretting a bit about this. I have 108" ceilings, and after many, many hours with the Ikea design tool I did figure out how to make everything line up at the same height, although wall cabinets could all be bumped down slightly if needed to align with the countertop cabinets.

The bottom of our upper Ikea cabinets are slightly less than 20" above the counter and with their 40" height, they go up to our ceiling (8' ceiling). We formerly had about 17" and the extra space is delightful. I'm 5'6" and the reach is not an issue. YMMV. Do what works for you.