I have a new monitor, which is 27', and the old one is 23.6'.

I convert my sensitivity with monitor distance methods and input the monitor size from 23.6' to 27'. The result is a slower sensitivity, and it does feel not right.

My thought is when you change to a bigger monitor, your FOV doesn't change, but your view gets zoomed in because it used to be a 23.6' monitor.

So I reverse the monitor size input, and it comes out with a faster sensitivity, and it feels better.

Is that my thought right? And is the calculation correct?

 

The concept behind using the monitor size in the conversion, is to keep the movement within the old monitor size consistent. In other words, to cover a cutout of 23.6 inches on your new 27" monitor, the movement should be the same. So for instance if you use MDH 100%, the mouse movement to move to the edge of your old monitor, should match the movement on your new monitor where the 23.6" would have ended. For this reason the sensitivity has to be slower, as with the same sensitivity you will of course cover the size of a 27" monitor with this movement, which is too fast.

This is not a FOV based conversion, it's purely based on the physical size of the monitor.

Note that using monitor size in the conversion is a concept that does not feel right for everyone. Personally I prefer the same sensitivity regardless of monitor size, but this is subjective.