Security Camera Lens Field of View Calculator
A 2.8 mm lens on a 1/2.8 inch sensor has a horizontal field of view of 84.9 degrees and covers about 18.2 feet of scene at 10 feet. Coverage width grows linearly with distance and pixel density falls in proportion.
Values update as you change the inputs. Where a figure cannot be computed honestly from what manufacturers publish, this calculator says so rather than showing a zero.
Gear that matches this answer
Chosen for this calculation.
REOLINK RLC-810A PoE Security Camera, 4K Wired Outdoor
$84.99The default 4K PoE bullet in this catalog: person and vehicle detection on the camera itself, so alerts are not triggered by every passing shadow.
- Resolution
- 8 MP
- Lens
- 4 mm
- Storage
- PoE, needs an NVR or NAS
Prices change often.
REOLINK PoE Security Camera RLC-810A 2 Pack, 4K, 100ft IR Night Vision
$194.99Two of the same camera, which is what most expansions actually need, at a lower price per unit than two singles.
- Resolution
- 8 MP
- Stated IR range
- 100 ft
Prices change often.
REOLINK RLC-1212A 12MP Bullet Outdoor PoE Camera
$129.99Twelve megapixels on a single camera, which buys real DORI identify distance on the one approach where you actually need a face rather than a shape.
- Resolution
- 12 MP
Prices change often.
Amcrest UltraHD 4K 8MP Outdoor Bullet Security IP PoE Camera, 98ft NightVision
$94.95Amcrest publishes its IR range and its lens focal length in the listing, which is rarer than it should be and is what makes a coverage calculation possible before you buy.
- Resolution
- 8 MP
- Stated IR range
- 98 ft
- Lens
- 2.8 mm
Prices change often.
Amcrest UltraHD 4K 8MP IP PoE AI Camera, 129 degree FOV, 49ft Color Nightvision
$109.99A 129 degree field of view covers a whole driveway from one mount, at the cost of pixel density: the wider the lens, the shorter the distance at which it can still identify anyone.
- Resolution
- 8 MP
- Field of view
- 129 degrees
- Stated IR range
- 49 ft
Prices change often.
Amcrest 5MP IP PoE AI Camera with 49ft Color Night Vision, Outdoor Bullet
$74.99Colour night vision rather than infrared monochrome, which preserves clothing and vehicle colour, the two details a police report actually asks for.
- Resolution
- 5 MP
- Stated IR range
- 49 ft
Prices change often.
The formula
field of view = 2 x atan(sensor width / (2 x focal length)), and scene width = 2 x distance x tan(field of view / 2)
The "1/2.8 inch" sensor naming is a legacy convention rather than a measurement, so the nominal widths used here are the figures the industry uses for each optical format.
Common questions
What field of view does a 2.8mm security camera lens have?
On the common 1/2.8 inch sensor format, a 2.8 mm lens produces a horizontal field of view of about 84.9 degrees and a vertical field of view of roughly 54 degrees. That wide angle is why 2.8 mm is the default lens on most fixed security cameras, trading reach for a broad view close to the camera.
How wide an area does a security camera lens cover at a distance?
Coverage width grows in direct proportion to distance from the lens. A 2.8 mm lens on a 1/2.8 inch sensor covers about 18.2 feet of scene at 10 feet away, so at 20 feet it covers roughly 36.4 feet, and at 40 feet roughly 72.8 feet, always exactly double the width covered at half the distance.
Does a longer focal length always mean a smaller field of view?
Yes, on the same sensor format a longer focal length narrows the field of view, because field of view equals twice the arctangent of sensor width divided by twice the focal length. A 2.8 mm lens gives a wide 84.9 degree view while a 6 mm lens on the same sensor narrows to roughly 44 degrees, trading width for reach at distance.
Does sensor size change field of view for the same lens?
Yes. A 1/2.8 inch sensor and a 1/1.8 inch sensor produce different fields of view from the identical focal length, because sensor physical width changes the underlying geometry, even though the 1/x inch naming is a legacy convention rather than a true measurement. A larger nominal sensor format generally produces a wider field of view at the same focal length.
Why does scene width matter more than field of view in degrees?
Degrees describe the lens itself, but scene width in feet describes what actually fits in frame at a specific distance, which is what matters when placing a camera over a driveway or door. Two lenses sharing the same field of view in degrees cover different actual widths once distance changes, so scene width at the real mounting distance is the more useful planning number.
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Keep going
A calculated figure is a planning number, not a promise. Every answer here comes from published standards and manufacturer specifications, and real installations vary with light, weather, scene motion and how a camera is actually aimed. Where a figure cannot be computed honestly from what manufacturers publish, this calculator says so rather than showing a zero.
Before you point a camera at anything. Aim at your own property and your own boundary, never into a neighbour's windows. Cameras in bedrooms, bathrooms or anywhere with a reasonable expectation of privacy are a serious legal problem, including for guests and anyone who works in your home. Audio is legally different from video, many US states require the consent of every party to a recorded conversation, and several recorders capture audio by default, so check your own state before enabling it. This is researched general information and not legal advice.