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.

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Your system

Resolution per camera
Codec
Frames/s
Hours/day recording
Recording mode
Total storage needed
0TB
—
0GB / day
0Mbps bandwidth
0Mbps / camera
0number of cameras
Retention per drive
Quick scenarios
0TB
0

How CCTV storage is calculated

Total storage is the data rate of all cameras multiplied by how long you record:

TB = Mbps/camera × cameras × hours × 3600 × days8 × 1000

The per-camera bitrate depends on resolution (2-8 MP), the codec (H.265 uses half of H.264) and the FPS. Multiply it by the number of cameras, the daily recording hours and the retention days; divide by 8 (bits→bytes) and 1000 (MB→GB) for the total GB. Then we recommend the next surveillance drive capacity up.

Example: storage for 4 cameras over 30 days

4 cameras at 4 MP in H.265, 15 fps, recording 24 h/day for 30 days:

  • Per-camera bitrate ≈ 5 Mbps × (15/30) = 2.5 Mbps.
  • 4 cameras → 10 Mbps total bandwidth.
  • Per day: 10 × 86,400 ÷ 8 ÷ 1000 ≈ 108 GB/day.
  • × 30 days ≈ 3.24 TB → a 4 TB surveillance drive covers it.

Step up to 8 MP (4K) and the system pushes past 6 TB over the same period.

CCTV storage FAQ

How much storage do I need for my cameras?
It depends on the number of cameras, their resolution, the codec, frame rate, recording hours per day and retention days. Enter your figures and the calculator gives the exact TB and a recommended drive.
Does H.265 really cut storage versus H.264?
Yes, roughly in half for the same quality. Almost all modern NVRs and cameras support H.265 (or H.265+), so it is the recommended choice to save space.
Continuous or motion-triggered recording?
This tool calculates continuous recording for the hours/day you set. Motion recording can cut storage by 30-70% depending on scene activity.
Which hard drive should I use for surveillance?
Surveillance-rated 24/7 drives (WD Purple, Seagate SkyHawk, Toshiba S300), not desktop drives: they are built for constant writes and many simultaneous streams.
Do I need RAID?
With many cameras or critical footage, yes: RAID adds fault tolerance so you do not lose recordings if a drive fails. The calculator reminds you from 8 cameras on.