CCTV Field of View Calculator

Use this free CCTV Field of View Calculator to determine the horizontal field of view and maximum image-detail distances achieved by a surveillance camera. The calculator estimates operational viewing distances using camera resolution, sensor size and lens focal length, helping designers select suitable optics for a defined operational requirement.

Results are presented using the latest IEC 62676-4:2025 image detail classifications, together with the equivalent legacy DORI categories for comparison with existing specifications and guidance

Understanding Image Detail

Modern CCTV design should begin with the operational outcome rather than the camera specification.

The calculator presents results using the latest OODPVCS classification introduced within IEC 62676-4:2025, together with the equivalent legacy DORI classifications.

Typical operational outcomes include:

  • Overview – Observe general activity within an area and maintain overall situational awareness.
  • Outline – Distinguish the outline or general shape of a person, vehicle or object from its surroundings.
  • Discern – Discern broad characteristics or actions, allowing the operator to interpret what is occurring.
  • Perceive – Perceive finer visual characteristics sufficient to support a more detailed understanding of people, objects or events.
  • Characterise – Characterise distinctive physical features or attributes that differentiate one subject from another.
  • Validate – Validate that a subject matches an expected person, vehicle or object by confirming known characteristics.
  • Scrutinise – Scrutinise the subject to obtain the highest practical level of image detail for detailed examination or evidential purposes.

Selecting the appropriate operational objective ensures the camera delivers the image quality required for its intended purpose without unnecessary cost or over-specification.

Lens Selection

Lens focal length has one of the greatest influences on CCTV system performance.

Short focal length lenses produce a wider field of view, allowing larger areas to be monitored but reducing image detail at distance.

Longer focal length lenses produce a narrower field of view with significantly greater image detail, making them suitable where identification or evidence-quality images are required over longer distances.

Selecting the correct lens is therefore a balance between scene coverage and operational performance