What Is Field of View (FoV)?
FoV is the angle (in degrees) of the game world visible on screen. A wider FoV shows more around you but makes targets look smaller and farther away. A narrower FoV zooms in but hides peripheral threats. Every FPS engine measures FoV slightly differently - some report horizontal, some vertical, and CoD famously reports 4:3 horizontal even on 16:9 monitors. This calculator converts between all of them.
Horizontal vs Vertical vs Diagonal FoV
- Horizontal (hFoV): angle left to right. Used by CS2, Valorant, Fortnite, Unreal-based games.
- Vertical (vFoV): angle top to bottom. Used by Apex Legends, Overwatch, Quake/idTech engine.
- Diagonal (dFoV): angle corner to corner. Less common but used in some cinematic games.
The three are linked by pure trigonometry. At 16:9 and 90 hFoV, you get about 59 vFoV and about 97 diagonal. At 16:9 and 90 vFoV, you get about 121 hFoV.
Hor+ vs Vert- Scaling
When you move from 16:9 to 21:9 (ultrawide), modern FPS games use Hor+ scaling: they keep the vertical FoV constant and extend the horizontal view to fill the extra width. That gives ultrawide players a real peripheral advantage. Older or console-ported games may use Vert- (cropping the top and bottom to preserve horizontal), which is penalizing on ultrawide. Our calculator assumes Hor+ - the standard for competitive FPS.
Further Reading
FoV is one leg of the aim stack. The other three are accurate DPI, a stable crosshair, and muscle memory. See how to copy a pro's crosshair in CS2 and Valorant and lock in the visual target that matches the FoV you just calculated.