I am not sure if I posted this a while back but its extremely useful for determining correct aspect ratio according to monitor size

for example I have a 16:9 monitor and I want to play the game in its equivalent 90 FOV, according to the calculations I would set my games fov to 106.26 deg to compensate

https://www.wsgf.org/fovcalc

theres also this site for static lookups based on popular settings:

https://web.archive.org/web/20250729121027/ht … _for_widescreen

In case the other site goes down