@DPI Wizard sorry for the late reply, I was on hollidays...
I dont know anymore what I exactly did, but I used:
Windows Sensitivity 3/11 and 1800 DPI
and I got: 0.628907 Sensitivity in CS GO.
I checked by moving my mouse from the center to one point at the end of my monitor (which I marked when my crosshair was at the center) and I also made a screenshot before moving my mouse. Than I used this screenshot and tested the mouse distance on my mousepad on the Windows screen. And 0.628907 seems to be correct for me.
There is no way the calculator is correct, or am I wrong? How I am getting the same sensitivity by calculating for 1800 or 1600 DPI ?