How to calculate CCTV storage
Each camera streams video at a bitrate measured in megabits per second. Multiply the bitrate by the seconds recorded per day and the number of days you keep footage, then convert bits to bytes.
GB per camera per day = Mbps × 3,600 × Hours ÷ 8 ÷ 1,000
Total GB = GB/day × Cameras × Days × Activity %
Example: 8 cameras, 4 MP H.265, 30 days continuous
3 Mbps × 3,600 × 24 ÷ 8 ÷ 1,000 = 32.4 GB per camera per day. × 8 cameras × 30 days = 7,776 GB, or 7.8 TB. With 10% headroom, use an 8.6 TB minimum, so a 10 TB drive.
Typical bitrates (15–20 fps)
| Resolution | H.264 | H.265 | GB/day (H.265, 24 h) |
|---|---|---|---|
| 1080p (2 MP) | 4 Mbps | 2 Mbps | 21.6 |
| 4 MP | 6 Mbps | 3 Mbps | 32.4 |
| 5 MP | 8 Mbps | 4 Mbps | 43.2 |
| 4K (8 MP) | 16 Mbps | 8 Mbps | 86.4 |
H.265 uses roughly half the storage of H.264 at the same quality. Busy scenes, night noise and higher frame rates raise the bitrate.
Frequently asked questions
How much storage does a 4K camera use per day?
About 86 GB per day recording 24/7 at 8 Mbps (H.265), or about 173 GB with H.264.
How many days will a 4 TB drive record?
With 4 cameras at 1080p H.265 (2 Mbps) recording continuously, about 46 days.
Does motion recording save space?
Yes. Recording only on motion typically cuts storage by 60–80%, depending on how busy the scene is.