A 4MP camera recording 24/7 in H.265 uses roughly 20 to 45 GB a day. So four cameras need about 4 to 6 TB for 30 days, and eight cameras about 8 to 12 TB. Use the formula below for your setup: GB per day = bitrate in Mbps × 10.8.
"How many days will it record?" is one of the first questions anyone asks about CCTV, and it is also where many cheap systems fall short. Here is how to work it out yourself.
The formula
Every camera sends a steady stream of data called the bitrate, measured in Mbps. You can see it in the recorder's camera or encoding settings.
GB per day = bitrate (Mbps) × 10.8
Multiply by the number of cameras and the number of days, and you have the space you need.
Example: 8 cameras at 4 Mbps for 60 days = 4 × 10.8 × 8 × 60 = 20,736 GB, about 21 TB.
Typical daily use per camera
These are typical figures for continuous recording with H.265. Busy scenes (a road, a shop floor) use more, quiet ones less.
| Camera | Typical bitrate | Per day | 31 days | 60 days |
|---|---|---|---|---|
| 2MP (1080p) | 2 Mbps | 22 GB | 0.7 TB | 1.3 TB |
| 4MP | 4 Mbps | 43 GB | 1.3 TB | 2.6 TB |
| 8MP (4K) | 8 Mbps | 86 GB | 2.7 TB | 5.2 TB |
How many days on each disk size (4MP cameras, 24/7)
The first number is standard H.265 at about 4 Mbps. The second is with a smart codec such as H.265+, which often roughly halves the bitrate on quiet scenes.
| Cameras | 4 TB | 6 TB | 8 TB |
|---|---|---|---|
| 4 cameras | 22 / 43 days | 32 / 65 days | 43 / 86 days |
| 8 cameras | 11 / 22 days | 16 / 32 days | 22 / 43 days |
| 16 cameras | 5 / 11 days | 8 / 16 days | 11 / 22 days |
Figures allow for the small part of each disk the recorder reserves. Treat them as estimates and check the real figure on your recorder after a week of recording.
What the rules expect
- Sharjah: commercial premises are commonly expected to keep at least 60 days. See our Sharjah Police CCTV guide.
- Dubai: many SIRA-regulated premises keep at least 31 days, and higher-risk activities longer. See our SIRA guide.
- Homes: there's no legal minimum. Two to four weeks is a sensible target.
Always confirm the current figure for your activity before buying disks.
Five ways to get more days
- Turn on H.265+ (or your brand's smart codec).
- Lower the bitrate on cameras covering quiet areas such as stores and corridors.
- Use motion recording for unimportant cameras and keep continuous recording for entrances and cash points.
- Add a second disk. Most 8 and 16 channel recorders take two or more.
- Use surveillance-grade disks built for 24/7 writing, not desktop disks.
Frequently asked questions
Does motion recording give me more days?
Yes, often several times more, because the recorder only saves video when something happens. But you may miss slow or partial events, and approved commercial systems usually need continuous recording.
Can I just use a bigger hard disk in my old recorder?
Each recorder has a maximum disk size per bay. Check the model's specifications or send us a photo of its label and we will tell you.
Is cloud storage an option?
For a few cameras, yes. For 8 or more cameras recording 24/7, local disks are far cheaper and don't depend on your internet upload speed.
Related
Menu names can differ slightly between models and software versions. Last reviewed 24 October 2026. Back to the help centre