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iRacing optimal FOV calculator.zip I wanted to share this information that was posted some time ago by David on the iRacing forums. I have seen some FOV posts and I myself did not give it much thought initially, I did find that I approached the FOV problem incorrectly, I setup my FOV based on my monitor angle. Doing this will allow you to maximize your FOV (i.e.179) but it will not correctly scale the interior of the car to the real world. To find your optimum FOV and match the real world size you need to determine the monitor angle first by using the width of your monitor. here is the equation monitor angle = 2 * inv(tan)(monitorWidth/2*viewingDistance) You can physically measure your monitor width or better yet look it up on the monitor specs. Viewing distance is easy to measure as you can use your sitting position to the front monitor from your eyes. There can be some margin of error here depending how you hold the measuring tape to your face and ensuring it runs level to the screen to get the accurate distance. Try to be in a relaxed position when doing this, as when you would be when in a race. 1.monitorWidth: In my case I use 27 inch monitors with a monitor width of 642mm (sorry I prefer metric to get more accurate results and it works better in the iRacing calculator). The conversion is inches * 2.54 * 10 = mm. 2. ViewingDistance My measured viewing distance is 610mm. so I get monitor angle = 2 * inv(tan)[642/1220] monitor angle = 2 * inv(tan)[0.5262295081967213] to calculate inverse tan, you can use windows calculator (put it into scientific mode ALT-2), enter the long number 0.5262295081967213 and then hit Inv then hit tan-1. You should get 27.754669264612328606718166212152, That number times 2 will give you the monitor angle that you should use at your particular sitting distance. In my case that is approximately 55.5 degrees. Multiply this number by 3 and you will get the maximum FOV value you should be using in game. So for me its 166. If I wanted to max out FOV at 179, and I can do this in game, the cockpit will move further away and its size will no longer represent the life sized view. In order to achieve 179, if that's what we want, we need to adjust the sitting distance or buy bigger monitors. Lets look at both scenarios now. so, starting with 179, we have to divide it by 3 to get the single angle between monitors 179 / 3 = 59.667 which is approximately 60 degrees for our analysis case 1 : viewingDistance We need to solve for viewingDistance from, monitor angle = 2 * inv(tan)(monitorWidth/2*viewingDistance) we derive, viewingDistance = monitorWidth / (2*tan(monitor angle / 2) viewingDistance = 642 / 2*tan(60/2) viewingDistance = 642 / 2 * 0.57735026918962576450914878050196 viewingDistance = 556 so to achieve a realistic size on screen with my 27 inch monitors to have a 179 FOV in game I have to sit 556mm from the screen. case 2 : monitorWidth (at original viewing distance of 642mm and monitor angle at 60) from, monitor angle = 2 * inv(tan)(monitorWidth/2*viewingDistance) we derive, monitorWidth = 2 * viewingDistance * tan(monitorAngle/2) monitorWidth = 2 * 609.6 * tan(30) monitorWidth = 703.9mm ok what do we do now. We need to calculate the hypotenuse. Recall ? S=OH C=AH T=OA (wikipedia it) Since we have the width, and we know the aspect ratio of the monitor 16:9 we can calculate out the optimal monitor size for this sitting distance to achieve 179 FOV at 60 degree monitors. We need to use C=AH. For this we need the angle between the bottom length of the monitor and the side height that runs along the diagonal. This is detemined by just using the monitor ratio. If you have a 16:9 monitor, then that angle is 29.36 and if you have a 16:10 monitor that angle is 32.01. Since I have a 16:9 aspect ratio monitor I will use 29.36. cos(angle) = adjacent length * hypotenuse cos(29.36) = 703.9 * hypotenuse hypotenuse = 703.9 / cos(29.36) H = 807.6mm or 31.8inches. So for my sitting distance to run a 179FOV with iRacing and get a realistic size (all this assuming iRacing built their calculator in game for this purpose) is to buy 32 inch monitors. Otherwise I need to sit a bit closer. Hope this makes sense and helps you out. Calculator attached.