Camera Field of View Calculator — FOV

Field of view is the lens-and-sensor marriage certificate: the same 50mm lens is a portrait lens on a phone and a wide on a medium-format body, because FOV is decided by focal length and sensor size together. Choose your sensor, enter the focal length, and this calculator returns the horizontal, vertical and diagonal angles your camera actually sees.

The Only Formula in Photography That Matters Every Day

For a rectilinear lens the geometry is one right triangle per dimension: the half-angle satisfies tan(θ/2) = (sensor dimension ÷ 2) ÷ focal length, so the full angle is 2 × atan(d ÷ 2f). Three consequences run the whole of photographic practice. FOV shrinks hyperbolically, not linearly, with focal length — the step from 24mm to 28mm changes the picture far more than 200mm to 240mm. The sensor is a full partner in the formula, which is why "crop factor" exists (divide the focal length by the crop and the angles follow the smaller sensor). And the three angles — horizontal, vertical, diagonal — are three different lenses' worth of description in one body setting, which is why manufacturers quote the diagonal and photographers argue about the horizontal. This calculator returns all three so whichever argument you are in, your number is on the line.

Worked Example: The Fifty on Full Frame

The defaults run photography's most famous pairing: a 50mm lens on a 36 × 24mm sensor. Horizontal: 2 × atan(18 ÷ 50) = 39.6°. Vertical: 2 × atan(12 ÷ 50) = 27.0°. Diagonal: the sensor's diagonal is √(36² + 24²) ≈ 43.3mm, giving 46.8° — the figure printed on a century of lens brochures. Now hold the lens and shrink the sensor in the calculator: on APS-C the same glass crops to the angles of a 75mm-class view (diagonal about 31°), which is the crop-factor phenomenon computed rather than recited. The 50mm did not change; the window did. That distinction — focal length is a property of the lens, field of view of the system — is the single most useful idea in lens selection, and this page is its calculator.

From Angles to Coverage: Framing a Real Space

Angles become practical when they are converted to coverage at a distance: width covered = 2 × distance × tan(horizontal angle ÷ 2), which the calculator prints for 10 metres in its note. Security-camera planning lives on this conversion (a camera's horizontal FOV and mounting distance decide whether a doorway is covered and at what pixels-per-metre identification quality), as do projector placement, VR headset specification (where FOV is the immersion budget and is quoted diagonally or horizontally by marketing convenience), and the astrophotographer's pairing of telescope focal length to sensor for a target's angular size. In every habitat the workflow is this page's: fix the sensor, vary the focal length until the angle fits the subject's angular size at its distance, then buy or mount accordingly.

FOV in Games and VR: Where the Number Is a Dial

Two industries turned field of view from a lens property into a user setting, and their conventions confuse everyone who crosses over. Game FOV sliders usually quote the horizontal angle (sometimes vertical, in older engines), and competitive players widen it toward 100–120° horizontal for peripheral awareness at the price of edge stretching — the same rectilinear geometry this calculator runs, pushed until the projection itself protests. VR headsets quote figures nearer the diagonal across both eyes' combined view, with per-eye horizontal angles near 90–110° in current hardware, and the number governs both immersion and motion comfort. The calculator's discipline transfers intact: ask which angle, on what sensor or display shape, before comparing any two FOV claims — in virtual optics as in glass, an unlabelled FOV is a marketing unit, not a measurement.

Equivalence, Demystified by the Formula

The internet's longest-running argument — whether a 35mm lens on APS-C "is" a 50mm lens — dissolves inside this page's triangle. Put 35mm against the APS-C sensor and the angles return ≈ the full-frame 50mm's: the framing is equivalent because the angle is the same, full stop. What is not equivalent is everything the formula does not contain: depth of field at the same aperture (the smaller sensor's is deeper), the f-number's light gathering per unit area, and the perspective, which belongs to camera position alone and was never the lens's to change. The calculator's discipline — angles from focal length and sensor, nothing else smuggled — is the argument's referee: state which property you mean, compute it in its own terms, and the equivalence wars lose their fuel.

Choosing a Lens From the Angle Backwards

Working photographers select glass in the calculator's reverse direction: the scene's required angle is known (a room's corner-to-corner span from the only place to stand, a stage from the press pit's fixed distance), and the focal length is the unknown — f = (d ÷ 2) ÷ tan(angle ÷ 2), the same triangle read backwards. Rental houses field this question daily ("what do I need for a 30-foot stage from 50 feet?": the stage subtends about 33.4° horizontally, so a full-frame lens near 60mm frames it, and the 35mm in the bag will waste a third of the sensor on the wings). Run candidate lenses forward through this page until the angle brackets the scene with working margin, and the bag packs itself — geometry first, gear second, as the formula has insisted all along.

Related Tools

More from the Other Calculators hub: the Depth of Field Calculator — what is sharp inside this field of view — and the Crop Factor Calculator for translating the same angles between systems.

Frequently Asked Questions

What field of view is a 50mm lens?

On full frame, 46.8° diagonal (39.6° horizontal) — the worked example. On APS-C, about 31° diagonal; on Micro Four Thirds, about 24°. The question has no sensor-free answer, which is the calculator's founding point: any FOV figure quoted without a format is a diagonal on full frame by silent convention, and misleading the moment the body changes. Enter your own format in the selector and the ambiguity dies on the spot, replaced by three angles you can defend.

Is human vision about 50mm?

The folklore needs its usual footnotes: the eye's total field spans roughly 200° horizontally including periphery, its sharp central (foveal) field only a few degrees, and its comfortable attended field somewhere near the 40–55° diagonal that normal lenses render — which is why 43–50mm photographs feel "natural" in perspective rendering on full frame. The calculator's "normal" band (35–55° diagonal) encodes that attended-field match. Your eyes remain wider and stranger than any lens in the selector; the comparison is about rendering, not anatomy.

Why does my phone's 24mm look wider than my camera's 24mm?

Because the phone's "24mm" is an equivalent focal length — the phone's real lens is about 5–6mm on its small sensor, yielding the same angles as 24mm on full frame, which is exactly what this calculator shows if you select the phone sensor and enter the true focal length. Camera lenses are labelled with real focal lengths; phone cameras are marketed with equivalents. Enter each device's real number against its own sensor here and the two systems become honestly comparable — usually to find they agree, the equivalence having done its job.

What FOV do I need for a security camera?

Work backwards from the scene: decide the width that must be covered at the distance where subjects will be, convert to the required horizontal angle (the coverage conversion in the framing section — the calculator's note performs it at 10 m; scale linearly), then choose the lens whose horizontal FOV meets it with a little margin. Narrow choke points (doors, tills) favour 60–90° horizontal; open areas traded against identification detail favour narrower. The perennial error is buying the widest lens and discovering faces are four pixels wide — coverage and resolution are the same budget spent two ways.

Does focusing change the field of view?

Slightly, on most lenses: focusing closer extends the lens from the sensor (or moves internal groups), effectively lengthening the focal length and narrowing the FOV — "focus breathing", notorious in video work when a rack focus visibly zooms the frame. The formula and this calculator use the infinity-focus focal length printed on the barrel; at portrait distances the true FOV is a touch narrower, by an amount that is lens-design-specific and unprintable on any general page. Macro work, where the effect is largest, has its own magnification-first arithmetic.

What about fisheye lenses?

They break the rectilinear assumption this calculator states in its note: a fisheye maps the world by a different projection (equidistant or equisolid-angle), squeezing up to 180° onto the sensor at focal lengths where the rectilinear formula would predict far less. The same 16mm that is a dramatic ultra-wide as a rectilinear design is a full fisheye as another. There is no single conversion — the mapping is the manufacturer's design choice — so fisheye FOVs are taken from the lens's own specification, and this page's honest scope is the rectilinear world.