How Long Does an 8TB Hard Drive Last for Security Cameras?
Estimate 8TB NVR retention for 4, 8 and 16 cameras using aggregate bitrate and continuous-recording math.
An 8TB NVR drive doubles the theoretical retention of a 4TB drive at the same aggregate bitrate, but camera count and encoding settings still dominate the result.
Continuous-recording examples
| System | Aggregate bitrate | Theoretical 8TB retention |
|---|---|---|
| 4 cameras × 2 Mbps | 8 Mbps | ~93 days |
| 4 cameras × 4 Mbps | 16 Mbps | ~46 days |
| 8 cameras × 4 Mbps | 32 Mbps | ~23 days |
| 8 cameras × 6 Mbps | 48 Mbps | ~15.4 days |
| 16 cameras × 4 Mbps | 64 Mbps | ~11.6 days |
These are pre-overhead estimates. Real usable disk capacity, metadata, audio, variable bitrate and the recorder's reserved space reduce actual retention.
When 8TB makes sense
Eight terabytes is a useful single-drive size for multi-camera systems that need more than a week or two of continuous history, especially when upgrading from a small factory-installed disk. It can also provide comfortable headroom for lower-bitrate H.265 systems.
When one 8TB drive is not enough
Sixteen high-resolution cameras, 30–90 day retention requirements and high-bitrate continuous recording can exceed 8TB quickly. At that point, multi-bay NVRs, larger surveillance drives or RAID/NAS designs become more appropriate.
Retention is an operational decision
Choose the history period from the incident you need to investigate. A homeowner may discover an event within a day; a business may not notice inventory loss or property damage for weeks. Storage should match that discovery window.
Use the NVR Hard Drive Calculator to model the required disk size. Compare with 4TB retention.