Free Tool · New 2026
CCTV Camera Lens & Field of View Calculator
Enter a camera's lens focal length and sensor size to estimate its horizontal field of view — the key number for deciding whether a lens will cover a wide area or is better suited to a narrow, longer-range identification shot.
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The field of view formula
Horizontal field of view = 2 × arctan(sensor width ÷ (2 × focal length)). A shorter focal length (e.g. 2.8mm) gives a wide field of view suited to general area coverage, while a longer focal length (e.g. 8-12mm or a zoom lens) narrows the field of view but lets you see identifiable detail — a clear face or license plate — from further away.
Choosing the right lens for a specific camera position
A single fixed-lens camera can't do both jobs well at once: covering a wide driveway and clearly identifying a face at the far end. This is exactly why gate cameras are often paired — one wide-angle camera for general coverage, one longer-focal-length camera aimed specifically at the point where identification matters, such as an intercom panel or a specific lane.
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Our free site survey includes a walk-through of exactly this trade-off for every camera position on your property.
Frequently asked questions
A moderate focal length (around 4-6mm) usually balances driveway coverage with identifiable detail on an approaching person or vehicle - a dedicated longer lens (8mm+) can be added specifically for plate or face capture.
Not necessarily on its own, but for the same camera resolution, a wider field of view spreads the same pixel count across a larger scene, so faces and plates appear smaller and less identifiable at distance.
1/2.8" and 1/3" sensors are very common in mainstream CCTV cameras - check your specific camera's datasheet, since this affects the actual field of view for a given focal length.
A varifocal lens lets you adjust the field of view after mounting to fine-tune coverage versus detail on site, which is useful when the exact distance to the target area isn't known until installation.