In this I know Matching FOV by changing resolution 

 I change 103Hfov to csgo (106.260205)  it“s usefull .  

but I change  csgo fov to 103fov but  nothing happen

 

In csgo The extra pixels are not hidden inside the display . I text apex and other game.they are all same

Force full screen in thise game When your game resolution is larger than the monitor resolution 

 this only works for making a smaller FOV bigger? 

The rendered image is larger than the screen, and it is wrong to crop the extra picture to make the FOV smaller, right?

 

 

 

B must always be less than A.  The angle of B is always a lower number that is becoming the angle of A. 

In your example, you need 1810X1018 with black bars with an input of 103 fov, to match 106.26 at native (1080p).

You also have to be 100% sure that is the fov you're inputting at the resolution you put it, or the mouse will feel decidedly different, since the focal calculation will be slightly off.