How Much Hard Drive Storage Does a CCTV System Need?
By the DC Fire & Security engineering team — installing and maintaining fire and security systems since 2010. Updated June 2026.
Quick answer
A typical 4-camera 4MP system recording continuously needs roughly 2TB for 30 days of footage. Eight 4MP cameras need about 4TB, and eight 4K (8MP) cameras need 8TB or more. Motion-only recording, H.265 compression and sensible frame rates can cut storage requirements by half or better.
How is CCTV storage calculated?
Storage = bitrate × cameras × hours recorded. Bitrate depends on resolution, frame rate, compression standard (H.264 vs H.265) and scene complexity — a busy street consumes far more than an empty corridor. The table below assumes continuous recording with H.265 at typical bitrates.
| System | 14 days | 30 days | 60 days |
|---|---|---|---|
| 4 × 2MP cameras | 0.5–1TB | 1–2TB | 2–4TB |
| 4 × 4MP cameras | 1–1.5TB | 2–3TB | 4–6TB |
| 8 × 4MP cameras | 2–3TB | 4–6TB | 8–12TB |
| 8 × 4K cameras | 3–5TB | 8–10TB | 16–20TB |
| 16 × 4MP cameras | 4–6TB | 8–12TB | 16–24TB |
How can I reduce storage without losing footage that matters?
- H.265/H.265+ compression: 40–60% smaller than H.264 with no visible quality loss — every system we fit uses it
- Motion or smart-event recording: corridors and yards that are empty 90% of the time don't need continuous recording
- Dual-stream recording: record the main stream at full quality and review remotely on a lighter substream
- 12–15 fps instead of 25 fps: smooth enough for evidence, nearly halves storage
- Per-camera scheduling: continuous on entrances and tills, motion-only elsewhere
Should I use surveillance-rated hard drives?
Yes. Desktop drives are designed for bursts of activity; CCTV writes 24/7. Surveillance-rated drives (WD Purple, Seagate SkyHawk) are engineered for continuous writing and multiple camera streams, carry firmware tuned for video, and fail far less often in recorders. The price difference is small; the cost of a failed drive is your entire archive.
Frequently Asked Questions
How long do businesses typically keep CCTV footage?
What happens when the hard drive is full?
Is cloud storage better than a hard drive for CCTV?
Can I add more storage to an existing NVR?
Need help from a professional installer?
We install and maintain fire and security systems across Bedfordshire, Hertfordshire and London — with fixed written quotes, a 36-month warranty, and certification your insurer will accept.
Request a free survey
Free site visit · No obligation · Response within 24 hours