CCTV DORI Calculator — Identify, Recognize, Observe and Detect Distances
Set your sensor, resolution, lens and distance to see field of view, pixel density and every DORI crossing distance — instantly, in metric or imperial.
Camera Optics
Configure physical parameters
HFOV
65.8°
VFOV
51.9°
DORI Key (EN 62676-4)
What is DORI?
DORI — Detect, Observe, Recognize, Identify — is the classification system defined by EN 62676-4, the European CCTV performance standard. It ranks how much visual detail a security camera can resolve at a given distance, based on pixel density: the number of camera pixels that fall across each metre of the scene.
- Identify — 250 px/m — enough detail for facial recognition or reading a licence plate.
- Recognize — 125 px/m — enough to confirm a known individual's identity.
- Observe — 62.5 px/m — enough to monitor general activity and body movement.
- Detect — 25 px/m — enough only to confirm a person or object is present.
The pixel density formula
Horizontal coverage width at a target distance is target distance × sensor width ÷ focal length. Pixel density is horizontal resolution ÷ horizontal coverage width, expressed in pixels per metre (px/m).
For example, with a 1/2.8" CMOS sensor, a 4MP — 2688×1520 camera, a 4.0mm lens and a 10m target distance, the horizontal coverage width is 12.9m, giving a pixel density of 208 px/m — inside the Recognize band.
Why published vendor pixel density figures disagree
A sensor-format label like 1/1.8" is nominal, not a single physical size — different vendors and calculator tools plug in slightly different real sensor dimensions for the same advertised format. This site's own two calculators prove it: this DORI calculator uses the datasheet-correct 7.18mm × 5.32mm for a 1/1.8" sensor, while the sibling FOV calculator is parity-locked to an older 7.18mm × 5.32mm pair for the exact same nominal label — two different published values behind one name, not a rounding error.
The cost is real: at a 4MP — 2688×1520 resolution, a 4.0mm lens and a 10m target distance, the 7.18mm pair gives 17.9m of horizontal coverage and 150 px/m, while the 7.18mm pair gives 17.9m and 150 px/m — a meaningfully different DORI classification from identical inputs. Secondary causes — rounding conventions, which FOV-angle convention is used, and the reference distance chosen — can widen the gap further, but the nominal-label mismatch above is the primary reason.
Metric and imperial DORI thresholds
DORI is defined natively in pixels per metre (px/m) by EN 62676-4, a metric European standard. The px/ft figures below are a derived approximation for imperial readers — each one computed by dividing its px/m threshold by 3.28 feet per metre — not an independently rounded number, which is why they read as odd decimals instead of clean round values.
- Identify — 250 px/m (76.2 px/ft)
- Recognize — 125 px/m (38.1 px/ft)
- Observe — 62.5 px/m (19.05 px/ft)
- Detect — 25 px/m (7.62 px/ft)
Frequently Asked Questions
What is DORI and where do the 25, 62.5, 125 and 250 px/m thresholds come from?
DORI — Detect, Observe, Recognize, Identify — is the image-quality classification defined by EN 62676-4, the European CCTV performance standard. Each of its four bands is defined by a minimum pixel density: 25 px/m is enough to detect that a person or object is present, 62.5 px/m to observe general activity, 125 px/m to recognize a previously known individual, and 250 px/m to identify someone with confidence. This calculator classifies your current configuration against those same four thresholds.
How is pixel density at a target distance calculated?
Pixel density in pixels per metre (px/m) is your camera's horizontal resolution divided by the horizontal coverage width at the target distance. Coverage width itself is the target distance multiplied by the sensor width and divided by the focal length. Move the target distance slider and this calculator recomputes both figures instantly.
Why does this calculator report a different DORI classification than the FOV calculator for the same 1/1.8" sensor?
A sensor-format label like 1/1.8" is nominal, not a single physical size — different vendors and tools use slightly different real sensor dimensions for the same advertised format. This calculator uses the datasheet-correct 1/1.8" dimensions; the sibling FOV calculator is parity-locked to an older, different pair for the same label. Same nominal format, two different published sizes, two different results.
Why do the px/ft figures show odd decimals instead of round numbers?
DORI thresholds are defined natively in pixels per metre by EN 62676-4. The px/ft figures shown in imperial mode are a derived approximation, each calculated by dividing its px/m threshold by 3.28084 feet per metre — not an independently rounded value — which is why they read as decimals rather than clean round numbers.
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