Camera Field of View and PPF Calculator
Pick a lens and see what it actually covers — and how far away a face is still identifiable. Free, no signup, and nothing leaves your browser.
The camera
At 30ft away
66.7pixels per foot
Recognise
Tell that it is somebody you already know.
- Angle · across
- 65.2°
- Angle · vertical
- 39.6°
- Scene width
- 38.4ft
- Pixels per metre
- 218.7
What it covers
Looking down on the camera. Drawn to the real angle, so a wide lens looks wide.
- Identifyto 26.2ft
- Recogniseto 52.5ft
- Observeto 105.0ft
- Detectto 262.5ft
What it misses underneath
From the side. Drawn to the real angle and the real height.
Blind spot
15.8ft
The top of the frame is at or above the horizon, so this camera is watching the sky behind whatever it is aimed at. Everything within 15.8ft of the wall is hidden.
How this is worked out
Angle of view. A lens and a sensor make a triangle. The horizontal angle is 2 × arctan(sensor width ÷ (2 × focal length)). That is why sensor size matters as much as millimetres: a 4mm lens on a 1/1.8 inch sensor is a much wider shot than the same 4mm on a 1/4 inch one.
Scene width. How much of the world fits across the frame at a given distance: 2 × distance × tan(angle ÷ 2).
Pixel density.Divide the camera’s horizontal pixel count by that scene width and you have pixels per foot. It is a density, not a total, which is why an 8 MP camera pointed down a long driveway can still be useless for identification: the pixels are there, just spread too thin where it matters.
The vertical angle, and the blind spot. The vertical angle comes from the horizontal one scaled by the picture’s aspect ratio — and we take that ratio from the resolution, not from the sensor format. Most IP sensors are natively 4:3 and crop to 16:9 for their headline resolution, so assuming the sensor’s shape gives a vertical angle half again too tall. Tilt the camera down by an angle and the bottom edge of the frame sits at tilt + vertical ÷ 2 below level; where that ray meets the ground is where the camera starts seeing, and everything nearer the wall than that is the blind spot.
The DORI bands. IEC 62676-4 defines four levels in pixels per metre: detect at 25, observe at 62.5, recognise at 125, identify at 250. In feet that works out to roughly 8, 19, 38 and 76 PPF. The range shown against each band is the distance at which this camera stops meeting it.
Horizontal, not diagonal. Every angle on this page is horizontal, because a floor plan is a view from above. Spec sheets usually headline the diagonal, which is the larger number — a 2.8mm lens on a 1/2.8 inch sensor is about 98° corner to corner but only 85° across. Type a diagonal in as if it were horizontal and the cone comes out too wide and the pixel density too low, which is why this tool checks the number you give it and says something.
One caveat worth stating plainly: this is the geometry, not a prediction of image quality. Low light, compression, a dirty dome, backlight and a subject in motion all cost you detail that the arithmetic does not know about. Treat the DORI range as a ceiling, and design with margin.
Common questions
- What is PPF, and how much do I need?
- PPF is pixels per foot: how much of the camera's horizontal resolution lands on each foot of the scene. It falls off with distance, because the same pixels spread across a wider view. The DORI standard (IEC 62676-4) sets the thresholds — roughly 8 PPF to detect that somebody is there, 19 to observe, 38 to recognise a person you know, and 76 to identify a stranger from the footage alone.
- Why does this disagree with my camera's spec sheet?
- Almost always because the spec sheet quotes the diagonal angle, corner to corner, and this calculator works in horizontal angle, which is what a plan view shows. The diagonal is the bigger number, so it is the one marketing prints. Tick the spec-sheet box and type it in: if it looks like a diagonal, the calculator says so rather than quietly using it.
- What is the blind spot of a CCTV camera?
- The ground directly beneath a wall or pole mount that falls under the bottom edge of the frame. Three things set it: how high the camera is, how far it is tilted down, and how tall its vertical angle of view is. It is the most common oversight on a high mount — a camera put up out of reach and left near level cannot see the door underneath it — and no amount of resolution fixes it. Tilting further down closes the gap and costs you range.
- Why is your vertical angle smaller than other calculators'?
- Because we take the aspect ratio from the resolution rather than assuming the sensor is 4:3. Most IP sensors are natively 4:3 and crop to 16:9 for their headline resolution, so a 4mm lens on a 1/2.8 inch sensor at 2688x1520 has a 40.2 degree vertical angle, not the 51.8 you get by assuming 4:3. That gap matters most for the blind spot: on a 3.5m mount tilted 15 degrees it is the difference between 4.0m and 5.0m of hidden ground, and the optimistic number is the wrong one to design against.
- Does sensor size matter as much as focal length?
- Yes, and it is the half people forget. Angle of view comes from the ratio of sensor width to focal length, so the same 4mm lens is noticeably wider on a 1/1.8 inch sensor than on a 1/4 inch one. If the spec sheet gives you a sensor format, use it.
- Is this the same maths FieldMarkup draws with?
- It is literally the same module. The cones in the editor, the coverage numbers in a submittal package and this page all call one shared optics library, so a number you get here and a number on a drawing cannot drift apart.
Drawing this on the actual floor plan
A number is one camera. A job is forty, and the question is which bits of the building nobody is looking at. FieldMarkup puts these cones on the plan itself — to scale, to the real angle, with the overlap shaded — and turns them into a coverage report you can hand to the customer.