Pixel ratio is calculated by dividing the sens- scaled yaw value (I.e degrees per count) by the amount of degrees in the centre of the screen over 1 pixel’s distance at any given FOV, which can be found as follows:
e.g for Counter Strike at 1920 x 1080 res:
yaw = 0.022 degrees;
sens = 0.5;
horizontal res = 1920 pixels;
horizontal FOV = 106.26 degrees;
Degrees per pixel distance = 2 * atan(tan(hFOV / 2 * pi / 180) / hRes) * 180 / pi = 0.0796 degrees;
Pixel ratio = yaw * sens / degrees per pixel distance = 0.138;