FOV Calculator

How the FOV Calculator works

The formula. To move a 4:3 setting to another aspect ratio, hFOV = 2 × atan(tan(FOV ÷ 2) × (new ratio ÷ 4/3)). For example, CS2's 90 at 16:9 is 2 × atan(1 × 1.333) = 106.3°. A second example: a 4:3 value of 60 becomes 2 × atan(0.577 × 1.333) = 75.2° at 16:9. The result is how many degrees of the world the setting actually shows on your screen.

"FOV 90" is not one thing. Games measure field of view along different axes and against different reference aspect ratios, and a monitor's shape changes how much of the world a given setting shows. This calculator converts between the conventions so that a number from one game, a guide or a friend's config can be reproduced in another.

Horizontal, vertical and diagonal. Horizontal FOV is the angle from the left edge of the screen to the right; vertical from top to bottom; diagonal corner to corner. They are linked by the aspect ratio through the tangent: tan(hFOV ÷ 2) = tan(vFOV ÷ 2) × (width ÷ height). Vertical FOV is what most engines store internally because it stays constant when the window shape changes, which is why a wider monitor shows more to the sides rather than less at the top.

The 4:3 convention. Source engine games, and Valorant and Apex which copied the scale, express FOV as the horizontal angle a 4:3 screen would show. CS2's fixed 90 means 90° on a 4:3 display; on 16:9 the same vertical FOV opens up to 106.3° horizontally. Overwatch 2, Apex's in-game slider and Call of Duty instead quote the horizontal angle on a 16:9 screen, so Overwatch's 103 is a smaller view than CS2's 90 would suggest at first glance: it works out to about 86 on the 4:3 scale. Choose the right convention in the second field and the calculator puts everything on one footing.

Ultrawide and 16:10. On a Hor+ game, a 21:9 monitor shows more at the sides for the same setting: CS2's 90 becomes 121° horizontal. On a 16:10 monitor it drops to 100°. The table gives these figures for every common ratio so you can decide whether to raise a slider after changing screens. Some games are Vert− instead and crop the top and bottom on wider screens; the calculator assumes Hor+, which is how nearly every modern shooter behaves.

Zoom and sensitivity. A narrower FOV magnifies the image, and the zoom line shows the factor relative to a 90° 16:9 view. That matters for aiming: the same mouse movement covers more screen at a narrow FOV, which is why converting sensitivity between games with different FOVs is not quite the same as matching cm per 360. Players who move between very different FOVs sometimes match the distance the crosshair moves on the monitor instead, scaling sensitivity by the ratio of the tangents of the two half-FOVs.

Practical range. Competitive shooters cluster between 90 and 110 horizontal on 16:9; higher shows more but makes distant targets smaller and can cause fisheye distortion above 120°. Console defaults are often 70 to 80 because players sit further from a television. Motion sickness is usually worse at low FOVs on a big monitor close up, so raising the setting is the first thing to try.

FOV calculator: CS2 FOV to 16:9 equivalents

A 4:3 horizontal FOV as CS2 and Valorant set it, shown on a 2560 × 1440 screen.

Horizontal, vertical and diagonal FOV at 16:9 for each 4:3 setting

Sources: Field of view in video games.

Checked against: 90° horizontal at 16:9 = 58.7° vertical

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