How much space each resolution uses
Resolution and codec determine the bitrate, that is, how much data each camera produces per second, and with it the disk you need. These figures are a guide for continuous 24-hour recording with H.265; the real bitrate depends on the scene and the camera settings.
| Resolution | Typical H.265 bitrate | GB per day per camera | 4 cameras, 30 days |
|---|---|---|---|
| 1080p (2 MP) | 2 Mbps | 21.6 GB | 2.6 TB |
| 4 MP (2560 × 1440) | 4 Mbps | 43.2 GB | 5.2 TB |
| 4K (8 MP) | 8 Mbps | 86.4 GB | 10.4 TB |
How to size the disk
Recording only on motion can cut the space needed by half or more, depending on how busy the area is. Work out your exact case in the CCTV storage calculator with the number of cameras, their bitrate and the days you want to keep, and buy a slightly larger drive to leave some headroom.
PoE or WiFi
PoE cameras get data and power through a single network cable from a PoE switch or an NVR with PoE ports. They are the most reliable option: they do not depend on WiFi coverage, do not suffer interference and keep recording even if someone jams the wireless signal.
WiFi cameras are easier to install, but they still need a power socket nearby and the picture can drop out if the signal is weak. They are reasonable for watching the inside of a home; for outdoor areas and businesses, run a cable whenever you can.
Resolution, lens and night vision
A 4 MP camera is the sweet spot for most people: it identifies faces and number plates at short and medium distances without blowing up disk usage. 8 MP (4K) cameras pay off when covering wide areas such as a yard or a car park.
The lens matters as much as the resolution: a 2.8 mm lens gives a very wide angle for nearby areas, while a 4 or 6 mm lens sees more detail at a distance. At night, infrared gives a black and white image; colour night vision cameras need some ambient light or a built-in spotlight.
Where to record: NVR, NAS or card
An NVR is a dedicated recorder with one or more drives; many include PoE ports and almost set themselves up with cameras of the same brand. Use surveillance drives such as WD Purple or Seagate SkyHawk, which are designed to record around the clock.
A NAS with Synology Surveillance Station, or a server running Frigate or Blue Iris, gives you more flexibility and smart detection. MicroSD cards are useful as a backup, but if someone steals the camera they take the recording with it, so they should not be your only copy.
Compatibility and the cloud
Choose cameras that support ONVIF and RTSP: that way you can record them on an NVR, NAS or software from any brand and you will not be tied to a single app. Be wary of cameras that only work with the manufacturer cloud and a monthly subscription.
If you want to watch the cameras from your phone, use the NVR app or a VPN rather than opening router ports to each camera.
Security, privacy and the law
Change the default password on every camera, update its firmware and, if your router or switch allows it, put the cameras on a separate network or VLAN without internet access. An exposed camera is a way into your network.
In the EU, if your cameras record areas outside your property or people other than your household, data protection rules apply: you usually need a visible sign and must not record the street beyond what is strictly necessary. Respect your neighbours privacy and point cameras only at your own property.
Frequently asked questions
How many days of footage should I keep?
At home, 7 to 14 days is usually enough to review any incident. Under GDPR in the EU, footage should not be kept longer than necessary; Spain, for example, requires surveillance recordings to be deleted within one month unless they are needed as evidence of a crime.
Which IP camera brand is best?
Hikvision, Dahua, Reolink, Ubiquiti UniFi and Axis cover everything from home use to professional installations. Rather than the brand, compare ONVIF support, H.265, night image quality and how often firmware updates are released.
Do I need a UPS for the cameras?
It is highly recommended: with a small UPS for the NVR and the PoE switch, the system keeps recording during a power cut, which is exactly when you may need it most.
Can I mix cameras from different brands?
Yes, as long as they all support ONVIF, although some advanced features, such as person detection, only work between devices from the same brand.