If you enter the monitor size, you will see the ratio It will not be the same for other games as it depends on the FOV, as stereo3D points out. I assumed default FOV for H1Z1.
Here's what you can do now as a workaround until I get the ratio calculator integrated. By using Windows as the "Convert from" game, you preserve the ratio in the conversion.
So first convert from CS:GO go to Windows. With sens 2, 400 DPI and default FOV you will get 350 DPI in Windows. Now this value is rounded to nearest 50, so you will need to adjust it slightly.
As you can see here, the ratio for CS:GO is 3.8977. Note that the ratio will change depending on monitor size and FOV even though DPI and sens are the same, and the monitor size needs to be same for both games!
Next, select Windows as your "Convert from" game, and adjust the DPI to get it as close to 3.8977 as possible. By selecting CS:GO as the "Convert to" game and entering 400 DPI, you can check that it converts back to sens 2 in CS:GO:
Now that you know 318.0118 (in this example) is your ratio, you can use this for any game
But a game like The Division has such a narrow sensitivity range that you need to go down to 250 DPI for the conversion to work:
It's a little tedious for now, but I'm working on the ratio calculator