Sim racing FOV calculator
Correct field of view is geometry, not preference. Enter your screen size and how far your eyes sit from it, and this returns the horizontal FOV that makes the virtual world the same size as the real one.
How to use this number
iRacing, Assetto Corsa Competizione, Le Mans Ultimate, and rFactor 2 all take a horizontal FOV. Enter 52 degrees directly.
Some titles ask for vertical FOV instead. Automobilista 2 and Project CARS 2 are the common ones. Use 31 degrees there.
If the number feels uncomfortably tight at first, that is expected. Correct FOV looks zoomed in compared to the default because most game defaults are set far too wide. Braking points and car placement get more accurate once your eyes adjust, because distances finally scale the way they do in a real car.
Why the maths is this simple
Your screen subtends an angle from your eye. That angle is fixed by two things only, the width of the screen and how far away it is. The calculator solves the same right-triangle relationship a camera lens obeys:
hFOV = 2 × arctan((screen width / 2) / eye distance)
Nothing about the graphics card, the sim, or the wheel changes it. A triple setup widens the total screen width, which is why triples allow a much larger correct FOV than a single panel at the same distance.