Monitor Field of View Calculator – Sim Racing FOV Calculator
Monitor Field of View Calculator. Enter your Screen Diagonal and Viewing Distance in this monitor field of view calculator to get the FOV your screen covers. Use the px to mm converter online to switch units in one click — no install or account needed.
Interactive Tool
The Monitor Field of View Calculator works out how many degrees of your vision a screen actually fills at your desk, which is the real variable behind every "what size monitor should I buy" question. Enter your Screen Diagonal, pick an Aspect Ratio, and type in your Viewing Distance to get the Horizontal FOV, Vertical FOV, and Diagonal FOV in degrees, along with where that lands on the immersive-gaming-to-productivity scale.
Your game has no idea how big your panel is or how far away you sit, so it guesses, and usually guesses wrong. This monitor field of view calculator takes three measurements (the diagonal, the aspect ratio and the distance from your eyes to the panel) and returns the exact angle your display fills in your vision, ready to type into iRacing, Assetto Corsa or any other sim.
How the Monitor Field of View Calculator Works
Think of the panel as a window into the 3D world. The field of view (FOV) is the angle between the lines running from your eyes to its left and right edges. Set the sim's virtual camera to exactly that angle and the scene matches your own perspective: a car 20 m ahead looks 20 m away and the cockpit looks life-size. The tool treats the panel as a flat screen viewed from its centre line, so the geometry stays simple and the picture realistic and immersive rather than stretched. The free screen size inches to cm converter converts your input instantly, right in your browser.
Screen Width from the Diagonal
Monitors are sold by the diagonal in inches, but the formula needs the physical width. Because the panel is a rectangle, Pythagoras splits the diagonal \(D\) using the ratio \(r\) (a 16:9 panel gives \(r = 1.778\)):
$$W = D \times \frac{r}{\sqrt{r^{2}+1}} \qquad H = D \times \frac{1}{\sqrt{r^{2}+1}}$$Multiply inches by 2.54 to get centimetres so both lengths share one unit.
The Horizontal FOV Formula
With \(W\) and the eye-to-screen distance \(d\) in the same unit, the horizontal FOV (hFOV) is twice the angle of a right triangle whose opposite side is half the panel:
$$\theta_h = 2 \times \arctan\left(\frac{W}{2d}\right)$$Code and spreadsheets return radians; multiply by \(180/\pi\) to get the degrees every sim expects. That one FOV calculation drives the whole tool: the horizontal field of view, the vertical angle and the seat for a chosen angle all reuse it.
Vertical FOV and Picture Height
Swap \(W\) for the panel's vertical size \(H\) and you get the vertical FOV (vFOV):
$$\theta_v = 2 \times \arctan\left(\frac{H}{2d}\right)$$Dividing your distance by \(H\) expresses the seat in picture heights: two panels of the same shape at the same multiple give identical angles, whatever their size. The calculator keeps full precision and rounds only what it displays.
Measuring Your Setup for the Sim Racing FOV Calculator
Three numbers drive the result; one matters most. Grab a tape measure and sit in your normal driving setup first. Run the screen diagonal to width height calculator tool to double-check a result before you rely on it for something important.
Screen Size and Aspect Ratio
- Screen size: the number on the box, measured across the visible picture only, never the bezel. Monitor size is rarely the input people get wrong.
- Aspect ratio: standard gaming monitors are widescreen, ultrawides use 21:9, super-wide models 32:9, and some office panels 16:10.
| Panel (eyes 70 cm away) | Panel span | Horizontal angle | Vertical angle |
|---|---|---|---|
| 24-inch widescreen | 53.1 cm | 41.6° | 24.1° |
| 27-inch widescreen | 59.8 cm | 46.2° | 27.0° |
| 32-inch widescreen | 70.8 cm | 53.7° | 31.8° |
| 34-inch ultrawide | 79.4 cm | 59.1° | 27.3° |
| 49-inch 32:9 | 119.8 cm | 81.1° | 27.1° |
Widescreen rows are 16:9 panels. Notice that the vertical angle barely moves across the last three: a wider panel adds side vision, not more sky.
Viewing Distance and Seating Position
Viewing distance moves the answer most. Set your seating position first (wheel, pedals, eye level), because ergonomics come before FOV, then measure from your eyes straight to the panel's centre. A sim rig or cockpit makes this repeatable; at a desk, mark where the chair sits. Enter the distance to screen in centimetres, converting from metres or feet if needed (1 ft = 30.48 cm). Every 10 cm of sitting distance shifts the result by several degrees.
Worked Example: FOV for a 34-Inch Ultrawide Monitor
Take a 34-inch 21:9 panel with your eyes 68 cm away. Step by step:
- Panel span: 34 × 2.54 × 2.333 ÷ √(2.333² + 1) = 79.4 cm, and 34.0 cm top to bottom.
- Horizontal: 2 × arctan(79.4 ÷ 136) = 60.5°.
- Vertical: 2 × arctan(34.0 ÷ 136) = 28.1°.
- Seat in picture heights: 68 ÷ 34.0 = 2.0.
So the recommended FOV for this panel is 60.5° horizontal or 28.1° vertical, depending on which axis your game reads. That FOV value sits far below the 90° many titles ship with: for 90° to be correct, you would have to sit just 39.7 cm from the glass.
| Eyes to panel | Horizontal | Vertical |
|---|---|---|
| 55 cm | 71.6° | 34.4° |
| 68 cm | 60.5° | 28.1° |
| 80 cm | 52.8° | 24.0° |
| 95 cm | 45.3° | 20.3° |
Working Backwards from a Target Angle
Rearranging the formula gives the seat distance for any target FOV:
$$d = \frac{W}{2 \times \tan\left(\frac{\theta_h}{2}\right)}$$Want a round 60° on the same single screen? \(d = 79.4 \div (2 \times \tan 30^\circ) = 68.7\) cm, just 7 mm behind the example seat. Use this target angle approach when planning where a new single monitor should go: a wider viewing angle always means a closer seat.
Finding the Viewing Angle for a 31.5-Inch Desk Rig
I race ACC and iRacing on a 31.5-inch 16:9 panel clamped to a desk, and I have one decision to make: is it worth pulling the monitor arm forward, or should I just set the numbers for where it sits now? The short answer: at 73.6 cm the panel fills 50.7° horizontally and 29.8° vertically, and moving it to 66.0 cm adds 5 degrees.
I measure from the bridge of my nose to the centre of the glass with the seat locked where my arms bend comfortably at the wheel: 73.6 cm, not the "about 70" I'd have guessed. I enter 31.5 inches, the 16:9 ratio, then the distance. The tool works out a 69.7 cm by 39.2 cm panel and returns 2 × arctan(69.7 ÷ 147.2) = 50.7° for iRacing and 29.8° for ACC. I check the horizontal one by hand with a phone calculator before trusting it; it matches to the decimal.
Then the sensitivity rerun, with the arm pulled forward by its full travel:
| Eyes to glass | iRacing (horizontal) | ACC (vertical) |
|---|---|---|
| 73.6 cm | 50.7° | 29.8° |
| 66.0 cm | 55.7° | 33.1° |
The calculator's 50.7° already sits above THX's widely quoted 40° home-cinema guideline, which I'd only reach by sitting 95.8 cm back. My judgement: the 66.0 cm position wins, because the wider field of view puts the apex in view earlier without distorting scale, and the numbers stay honest as long as I enter them after the move.
The catch nobody mentions is eye level. My eyes sit 11.5 cm below the panel's centre, and the true vertical angle there is 29.2°, not 29.8°. The gap looks trivial, but every sim draws a symmetric view as if your eyes were dead centre, so no FOV value can fix an off-centre seat. I lower the arm until my eyes line up with the middle of the picture, then type 55.7 into iRacing and 33.1 into ACC. Distance is the input I'd watch on any desk rig: one notch on a monitor arm moves the result more than any choice of panel ratio.
Triple Screen FOV and Side Monitor Angle
With triple screens, your sim needs the field of view of one panel and your rig needs the toe-in for the two side monitors. Measure one display (all three should match), choose the triple monitors mode and add your bezel width. The tool treats each panel plus its bezels as one chord of a circle around your head, and because every chord covers the same angle, the side monitor angle (how far each outer panel turns in from the centre screen's plane) equals the per-panel angle. Most sims want only the single-panel figure once triple mode is on.
Bezel Width and the Triple Screen Angle
Enter the bezel thickness of one edge only, in millimetres. For three 24-inch widescreen panels 58 cm from your eyes with 7 mm frames, each panel plus frame spans 54.5 cm and covers 50.4°, so the triple screen angle is 50.4° and the total FOV is 151.1°. Ignore the bezels and you'd angle the outer panels at 49.2°, a 1.2° error that kinks the road at every gap.
Curved Monitor FOV and Curve Radius
A curved monitor wraps its edges toward you, so the same panel covers more of your vision than a flat one. The fix is arc geometry: the panel becomes an arc on a circle whose curve radius \(R\) is the 1000R, 1500R or 1800R on the spec sheet (in millimetres), and the angle is measured from your eye, which sits closer than that circle's centre:
$$\theta_h = 2 \times \arctan\left(\frac{R\sin\alpha}{R\cos\alpha - (R - d)}\right), \qquad \alpha = \frac{W}{2R}$$Bend the example's 34-inch panel to 1500R and the angle rises from 60.5° to 64.0°; at 1800R it is 63.5°, at 1000R 65.4°. A few degrees, but enough to feel.
Entering the FOV Value in Your Game Settings
Every simulator describes the same physical angle its own way, so one setup produces different numbers per title. First check whether the in-game FOV setting is horizontal, vertical or a slider. If your result falls outside the allowed range, use the nearest limit or move the seat.
iRacing, Automobilista 2 and BeamNG
iRacing and Automobilista 2 take the horizontal angle directly, so the example rig enters 60.5. BeamNG.drive labels its slider horizontal but reads the vertical angle, so it takes 28.1. Formula titles such as F1 25 skip degrees entirely and use an abstract slider, which means converting the angle with a community-measured mapping instead of typing it in.
Assetto Corsa, ACC, rFactor 2 and Le Mans Ultimate
These four read vertical FOV, so the same rig enters 28.1. rFactor 2 and Le Mans Ultimate share an engine and behave identically; in ACC, leave the FOV offset slider at zero and move your seat in the camera menu instead. Tape both numbers beside your rig and you never recalculate when you switch titles.
Why the Correct FOV Feels Too Narrow at First
Default FOV settings suit a TV across the room, often 90° or more on one panel, which looks dramatic but is too wide at a desk: corners arrive early and speed feels exaggerated. Switch to a field of view that matches your seat and the view seems cramped, because mirrors and side windows leave your peripheral vision. Give it a week before judging. A VR headset avoids the question, since its optics fix the angle; leave the sim at the headset's native FOV.
Sim Racing Lap Times and Braking Points
The correct FOV doesn't make the car faster; it gives your eyes reliable visual feedback. Braking points line up with the physics, spatial awareness improves in traffic and distance perception holds steady, so lap times usually fall as your stopping becomes repeatable. Those gains arrive only with the calculator's own result entered; racing on a guessed angle trains you to react to false cues.
Camera Angle of View vs Screen FOV
Photographers use the same trigonometry, which is why a camera field of view calculator turns up in the same searches. In photography, the angle of view is what a lens and sensor capture, and the field of view is how much scene that angle spans at a given distance. For a monitor, your seat fixes the distance, so the two merge into one number.
Focal Length and Sensor Size
$$\text{AOV} = 2 \times \arctan\left(\frac{s}{2f}\right)$$It is the panel formula again, with the sensor size \(s\) in place of the panel and the focal length \(f\) in place of your eye distance. A full-frame camera (36 × 24 mm) behind a 35 mm lens has a 54.4° horizontal angle of view and 37.8° vertically; a shorter lens widens a camera's angle of view.
Linear Field of View at a Distance
$$\text{FOV}_{\text{linear}} = 2 \times d \times \tan\left(\frac{\text{AOV}}{2}\right)$$At 10 m, that 35 mm setup frames a scene 10.3 m wide and 6.9 m tall. Turned around, the full-frame camera matching your 60.5° monitor angle carries a 30.8 mm lens: a correctly set sim shows the road as a 31 mm lens would.
Frequently Asked Questions
- What FOV should I use for sim racing?
- There is no single best number: the correct FOV is the angle your own screen fills from your own seat. Enter your screen size, aspect ratio and eye-to-screen distance and use the result for your game. A 34-inch 21:9 ultrawide at 68 cm, for example, fills about 60.5° horizontally and 28.1° vertically.
- Should I enter horizontal or vertical FOV in my game?
- It depends on the title. iRacing, Automobilista 2, Project CARS and the truck simulators read horizontal FOV, while Assetto Corsa, ACC, rFactor 2, Le Mans Ultimate, RaceRoom and BeamNG.drive read vertical FOV. DiRT Rally and GRID Autosport want double the vertical value, Richard Burns Rally uses radians, and F1 and EA Sports WRC use sliders, so the calculator lists a value per game.
- Why does the correct FOV feel so narrow?
- Most games ship with a wide default meant for a TV across the room. A physically correct angle at desk distance is much smaller, so mirrors and side windows drop out of view at first. Give it a few sessions; distances and braking points become far easier to judge.
- What if my calculated FOV is outside the game's range?
- Set the closest value the game allows. If it is below the minimum, move the screen closer or use a larger screen to bring the correct angle into range.
- How do I measure the distance to my screen?
- Sit in your normal driving position with the seat, wheel and pedals already adjusted, then measure with a tape measure from your eyes straight to the centre of the screen. This distance changes the result more than any other input, so measure rather than guess.
- What angle should my side monitors be at with triple screens?
- Each side panel should turn inward by the same angle that one panel covers from your seat, including its bezels. The calculator shows this as the recommended side monitor angle and compares it with the angle you enter for your rig.
- What is the difference between angle of view and field of view?
- The angle of view is an angle, in degrees, and does not depend on distance. Field of view can also mean the width that angle covers at a given distance, which grows as you move further away. For a monitor your seat fixes the distance, so the calculator reports the angle.