FOV Calculator
Enter a horizontal field of view and your aspect ratio to get the matching vertical FOV in degrees — and see why widescreen and ultrawide screens need different settings.
Horizontal to vertical FOV
Enter the horizontal FOV your game uses and the screen aspect ratio, and the calculator returns the matching vertical field of view in degrees.
Mind the aspect ratio
The wider your screen, the smaller the vertical FOV for the same horizontal setting — enter width ÷ height (16:9 = 1.7778) before you start.
What does an FOV calculator do?
Horizontal and vertical field of view
An FOV calculator converts the horizontal field of view a game gives you into the vertical field of view that matches it on your screen. Field of view is the angular slice of the scene the camera shows, measured in degrees, and most engines expose only the horizontal angle. Because screens are wider than they are tall, the vertical angle is always smaller and depends on the aspect ratio. This tool takes two numbers — the horizontal FOV in degrees and the aspect ratio (width divided by height) — and returns the vertical FOV, so you can match the same view across a 16:9 monitor, a 21:9 ultrawide, or a 4:3 display.
Enter a horizontal FOV in degrees and your aspect ratio to get the matching vertical field of view instantly.
The vertical FOV is twice the arctangent of the horizontal half-angle's tangent divided by the aspect ratio.
Vfov = 2 × arctan(tan(Hfov / 2) / aspect ratio)The horizontal FOV is halved and run through the tangent, divided by the aspect ratio, then turned back into an angle with the arctangent and doubled. Angles go in and out in degrees, while the tangent works internally in radians. At a 1:1 aspect ratio the vertical FOV equals the horizontal FOV; the wider the screen, the smaller the vertical result.
Suppose a game is set to a 103° horizontal FOV on a standard 16:9 monitor (aspect ratio 1.7778).
Halve the horizontal FOV
103° / 2 = 51.5° — the horizontal half-angle that drives the conversion.
Divide the tangent by the aspect ratio
tan(51.5°) ÷ 1.7778 ≈ 1.2572 ÷ 1.7778 ≈ 0.7072 — the scaled vertical tangent.
Take the arctangent and double it
2 × arctan(0.7072) ≈ 2 × 35.27° ≈ 70.5° — the vertical field of view.
The vertical FOV tells you how much of the scene you see from top to bottom, and it is the number that actually stays fixed when you change monitors. Games almost always let you set the horizontal FOV, but a 103° horizontal setting looks very different on a 16:9 screen (about 70.5° vertical) than on a 21:9 ultrawide (about 58.7° vertical), because the extra width on an ultrawide is added at the sides while the top and bottom stay roughly the same. If you switch to a wider display and keep the horizontal FOV constant, your vertical view shrinks and the world can feel more zoomed-in vertically. To keep the experience consistent — especially in competitive shooters where vertical awareness matters — many players fix a target vertical FOV and recompute the horizontal setting for each aspect ratio. This calculator makes that translation explicit: pick a vertical FOV you like, then adjust the horizontal value until the vertical result matches across every screen you play on.
The formula is exact for standard rendering, but a couple of points are worth keeping in mind.
Assumes a rectilinear projection
This conversion assumes the standard rectilinear (pinhole) projection that virtually every 3D engine uses, where straight lines stay straight. It does not describe fish-eye, panini, or other curved projections, and it ignores per-game FOV scaling quirks — some titles internally treat the slider as a vertical or "Hor+" value. Enter the aspect ratio as width divided by height (16:9 = 1.7778, not 9 ÷ 16) so the vertical FOV comes out correct.