CCTV Disk Calculator
Enter your cameras, resolution, codec and retention days — get the total disk storage in TB, the bandwidth, and the surveillance drive you need, in real time.
Your system
How CCTV storage is calculated
Total storage is the data rate of all cameras multiplied by how long you record:
The per-camera bitrate is based on Hikvision's recommended bitrate tables for H.264 and H.265: at 30 fps in H.265, 2 MP (1080p) = 2048 kbps, 4 MP = 4096, 5 MP = 4608 and 8 MP (4K) = 8192; in H.264, double. It does not scale linearly with FPS: Hikvision recommends the same bitrate at 25 as at 30 fps, 75% at 20 fps and half at 15 and 12.5 fps (we also use that half for 12 fps). That is the figure for a normal scene; Hikvision advises raising it by 20-30% for more complex scenes.
Multiply it by the number of cameras, the daily recording hours, the retention days and the share of time actually recorded (100% for continuous; 60, 35 or 20% in the motion modes, our own estimate); divide by 8 (bits→bytes) and 1000 (MB→GB) for the total GB. Then we recommend the smallest surveillance drive that holds it, counting 98% of its capacity as usable. If your recorder shows 3.64 TB on a 4 TB drive, no space is missing: it is the same capacity in TiB.
Example: storage for 4 cameras over 30 days
4 cameras at 4 MP in H.265, 15 fps, recording continuously 24 h/day for 30 days:
- Per-camera bitrate = 4.096 Mbps × 0.5 (15 fps) ≈ 2.05 Mbps.
- 4 cameras → 8.2 Mbps total bandwidth.
- Per day: 8.192 × 86,400 ÷ 8 ÷ 1000 ≈ 88.5 GB/day.
- × 30 days ≈ 2.65 TB → a 4 TB surveillance drive covers it.
Step up to 8 MP (4K) and the system reaches 5.31 TB over the same period: you need a 6 TB drive.
Methodology & sources
Every result is computed in your browser with the formula shown above — nothing is sent to a server. The numeric model is based on this data and these references:
- Hikvision — H.264(5) & H.264(5)+ Recommended Bit Rate at General Resolutions (recommended H.264/H.265 bitrate by resolution and fps)
- Share of time recorded in the motion modes (60/35/20%): our own estimate; the real share depends on the scene and the detection sensitivity.
- Drive capacity in decimal TB, the way drives are sold (4 TB = 4·10¹² bytes). We count 98% as usable to leave a margin: the file system takes under 1%.
Formula reviewed and verified against real-world cases.