Recognition distance

CCTV Recognition-Distance Calculator

How far away can a camera still recognise someone you already know? Enter the resolution, lens and sensor to get the distance at the DORI “recognise” threshold of about 125 px/m — plus the stricter identify distance and the far looser detect distance for context. Planning figures; runs in your browser.

Resolution

Focal length (mm)~2.8 wide, ~4 general, ~12+ telephoto

Sensor size

Recognise a known person up to

0.0 m

at ~125 px/m — enough detail to know a familiar face

0.0 m

Identify (250 px/m)

stricter — a stranger’s face

0.0 m

Detect (25 px/m)

looser — someone is there

Recognise means you can tell it is a person you already know. It sits between identify (250 px/m — strict enough to name a stranger) and detect (25 px/m — just enough to spot that someone is present). Push the subject past the recognise distance and a familiar face turns into an anonymous shape.

Planning estimate only — this is a geometric pixel-density limit. Real recognition also depends on light, subject motion and video compression, all of which shorten the usable distance, and sensor widths vary by model. Use it to compare lenses, then confirm with a live site test.

Plan the rest of the coverage

Full lens & FoV calculator Identification distance Detection distance CCTV coverage planning

Related Guides — Deep-dive reading

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Related Tools — You may also find these useful

CCTV Lens & Field-of-View Calculator

Focal length, sensor and resolution to field-of-view angle, scene width and DORI detect/observe/recognise/identify distances.

Lens & FoV

CCTV Detection-Distance Calculator

How far a camera can still detect that someone is present (DORI 25 px/m), with observe, recognise and identify for context.

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CCTV Identification-Distance Calculator

How far a camera can still identify a face or number plate (DORI 250 px/m), from resolution, lens and sensor.

Identify Distance