I don't know how to calculate the ratio from 16:9 to 4:3

[11111111]

too complicated

[fortunate reee]

you dont have to calculate in this way unless you have soemthign special you are trying to achieve.

this would be the default you wann start with for csgo https://www.mouse-sensitivity.com/?share=3fd1808afd4677d69a2661f5d7f159fd

maybe change your resolution and aspect ratio to fit your setup

 

if you then want to match csgo to other games you simply add them in the 2nd slot

https://www.mouse-sensitivity.com/?share=a9adf0204e031b713ff8868c879e7f13

like this ^ and you should be all done. if you are usign stretched resolution or aspect stuff  this will be the spot you shoud edit.

 

if you are having specific issues dont hesitate to Ask