No, no kitchen unit under a window. At that time, we considered which height for the windowsill we would like, and we came up with 87.5. But that has nothing to do with the kitchen.
we also have a windowsill height of 104.5 cm in the kitchen. Screed and floor covering will be deducted from this, so that we arrive at a final height of the kitchen countertop of about 90-91 cm. The countertop then runs directly into the window. Our builder also put a thin Styrodur board on the window reveal.
With us, the floor construction is higher. In addition to screed, for example, insulation and underfloor heating are also added. That’s why it’s 20cm. For you, it would be "only" about 14cm...
Just out of interest: Why do you want a specific parapet height?
So that, for example, our kitchen countertop can run exactly into the window. Otherwise, I wouldn't care either; for the other windows, we simply chose a stone size that can easily be built in.