Free tool
How Many CCTV Cameras Do I Need
Get a camera count for your building along with the resolution each area needs, the recorder channels, the storage in terabytes and the cable to run it.
Describe the building and this works out how many cameras it takes to cover it properly, what resolution each area needs, how many recorder channels that means, and how much storage the footage will actually use. The numbers come from the same rules we use when quoting a real installation.
Camera by camera
| Area | Cameras | Resolution | Type | Why |
|---|
Equipment to run them
Resolution is about identification, not sharpness
The useful question is never how many megapixels a camera has. It is whether the footage can identify a face or read a number plate at the distance that camera is mounted at. The European standard for this measures pixels across the subject: roughly 250 pixels per metre to identify someone, 125 to recognise a person you already know, and 25 to simply see that somebody is there.
That is why the table above puts higher resolution on entrances and vehicle access and accepts less inside a small room. A 2 megapixel camera over a doorway at two metres will identify a face easily. The same camera watching a thirty metre warehouse aisle produces footage where everybody looks like the same grey shape, which is useless at precisely the moment you need it.
Where the storage figure comes from
Storage is the number most quotes get wrong, almost always downward. It is calculated from the bitrate each camera produces, multiplied by the hours it records each day, multiplied by the days you want to keep. Compression makes an enormous difference: H.265 uses around forty percent less than H.264 for the same picture, and smart coding saves more again on a quiet scene by spending bits only where something moves.
Motion recording saves a great deal but is less reliable than it sounds. A camera facing a busy street, a tree in the wind or a car park at night with headlights sweeping through will trigger far more than twelve hours a day, and the drive fills long before the retention period you were promised. If the footage matters legally, size for continuous recording and treat motion detection as a bonus.
The things the count cannot know
Layout beats arithmetic. One well placed camera at the top of a stairwell can replace three in corridors. A single pillar in the middle of a shop floor can force an extra camera that no formula predicts. Lighting matters just as much: a camera pointed at a glass entrance will be blinded every afternoon unless it is positioned to avoid the sun, and the cheapest fix is almost always moving it rather than buying a better one.