Storage is the most common thing people get wrong with CCTV. A recorder that keeps four days instead of thirty is not a recorder you can rely on after an incident that was noticed a week later.
The formula
Storage per day (GB) = bitrate (Mbps) x 10.8 Total storage (TB) = per-day GB x cameras x days / 1000
Bitrate is the video data rate per camera, shown in the recorder's camera settings. 10.8 is the number of gigabytes produced per day by 1 Mbps.
Worked examples
Villa: 6 cameras, 4 MP, 30 days
Assume 4 Mbps per camera with H.265. 4 x 10.8 = 43.2 GB per camera per day. For 6 cameras, 30 days: 43.2 x 6 x 30 = 7,776 GB, about 7.8 TB. In practice, motion recording or smart codec settings can lower this.
Shop: 8 cameras, 2 MP, 60 days
Assume 2 Mbps. 2 x 10.8 = 21.6 GB per camera per day. For 8 cameras, 60 days: 21.6 x 8 x 60 = 10,368 GB, about 10.4 TB.
Warehouse: 16 cameras, 4 MP, 31 days
4 x 10.8 x 16 x 31 = 21,427 GB, about 21.4 TB. Add a safety margin of 10-20 percent.
Allow for overhead
Recorders reserve some disk space and the real bitrate varies with the scene. Add 10-20 percent.
Ways to stretch storage
- Use H.265 or smart codec (H.265+) to cut the bitrate.
- Reduce frame rate on low-risk cameras; 12-15 fps is fine for corridors.
- Lower the bitrate on quiet areas.
- Motion recording on non-critical cameras; keep continuous recording at entrances.
- Add disks if the recorder has free bays.
- Do not drop resolution on the cameras that identify people.
RAID and redundancy
Larger systems often use RAID so one disk failing does not lose footage. Regulated premises may be expected to protect against disk failure. See Sharjah Police CCTV requirements for the commonly applied points and check yours.
Check your real figure
After a week of recording, check how many days the disk holds in the recorder's storage menu and compare it to your calculation. If the number is lower than expected, find out why before you need the footage.
How many days do you need?
There is no single answer. See how long CCTV footage is stored in the UAE. For quick tables and examples, use our help centre guide.
Get it sized for you
We size recorders from your camera list and the days you need. Request a CCTV quote.
Conclusion
Work out bitrate, multiply by days, add a margin, and verify after a week. Ten minutes of arithmetic prevents the most common CCTV disappointment.
Frequently asked questions
Why is my recorder keeping fewer days than expected?
Common causes are a high bitrate, motion-heavy scenes, extra cameras or a disk reserved partly for other uses. Check the bitrate per camera and the free space on the disk.
Do I need special hard drives?
Yes. Surveillance-grade drives are designed for continuous writing. Desktop drives tend to fail sooner in a recorder.
