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CCTV storage and bandwidth

Enter cameras by group and the retention period to see how many TB to store, how many drives to buy with RAID, how many recorders to use and whether switch uplinks can carry the traffic.

Pre-sizing and estimating tool: results do not replace design, calculations or reports signed by a licensed professional, nor verification against the applicable codes and standards.

Pre-sizing
Camera group 1
Camera group 2
Camera group 3
More groups? Paste the list from Excel

One row per group: name (optional); quantity; resolution in MP; fps; codec (H.264, H.265 or H.265+); % of day recording; bit rate in Mbit/s (optional). Medium quality is assumed.

See what was read
Recording and disks

Use surveillance-rated drives (24/7 writing). Capacity in decimal TB, as on the drive label; the operating system shows about 9% less (TiB).

Network
—Storage required
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Storage and bandwidth by camera group

Bars: storage over the retention period, without headroom. Points: group bandwidth on the network.

Tap the chart to see the values.

Storage versus retention days

Required with headroom, compared with the usable capacity of the disks calculated.

Tap the chart to see the values.

The report gathers this page's inputs, results, equations, assumptions and references, with fields for project, engineer and revision. In the print dialog, choose Save as PDF.

Method, assumptions and references

Equations used

Rate per camera R = R₂₆₄,₃₀ (resolution) × codec factor × quality factor × (fps ÷ 30)^0.8, or the value entered
R₂₆₄,₃₀ (Mbit/s): 1 MP 2; 2 MP 4; 3 MP 5; 4 MP 6; 5 MP 8; 8 MP 12; 12 MP 16. Codec: H.264 1; H.265 0.5; H.265+ 0.3. Quality: low 0.7; medium 1; high 1.4
Storage (TB) = Σ n · R · recording fraction × 86,400 s × days ÷ 8 ÷ 10⁶; with headroom × (1 + h)
Usable capacity: no RAID n · C; RAID 5 (n − 1) · C; RAID 6 (n − 2) · C; RAID 10 n ÷ 2 · C
Network bandwidth = Σ n · R × 1.10 (IP/RTP overhead); uplink: highest-rate cameras on the same switch

Assumptions and limits

  • Typical manufacturer rates for the main stream; the actual rate depends on the scene (foliage, rain, night noise and traffic raise it a lot). The 0.8 fps exponent is an approximation: fewer frames cut the rate less than proportionally.
  • Cameras stream all the time, even with motion-only recording. Secondary viewing streams, edge (SD card) recording and cloud storage are not included.
  • Capacity in decimal TB (10¹² bytes). Headroom covers the file system, indexes and rate variation.

Standards and technical documents

  • IEC 62676-4:2014: Video surveillance systems for use in security applications — Part 4: Application guidelines
  • ITU-T H.264: Advanced video coding for generic audiovisual services
  • ITU-T H.265: High efficiency video coding
  • ONVIF Profile S and Profile T specifications
  • SNIA: Common RAID Disk Data Format Specification (DDF)

U.S. regulations

  • NFPA 731: Standard for the Installation of Electronic Premises Security Systems
  • 18 U.S.C. § 2511 (Wiretap Act): limits on recording audio; state laws on video in private areas
  • UL 2802: performance testing of camera image quality

Frequently asked questions

How many TB do I need for 30 days of recording?

Multiply each camera’s bit rate by recording time. A 2 MP H.265 camera at 15 fps produces about 1.15 Mbit/s, or 12.4 GB per day; over 30 days, 0.37 TB. With 24 cameras, 8.9 TB before headroom.

How much does H.265 save over H.264?

About half the bit rate at the same quality. Smart codecs such as H.265+ reach 30% of the H.264 rate in static scenes but gain little in busy scenes.

Which RAID level should an NVR use?

RAID 5 is fine for a few drives up to 8 TB. With 12 TB or larger drives, use RAID 6, which survives two failures: rebuilding a large drive takes days.

Is there a required CCTV retention period in the U.S.?

There is no general federal rule. Retention is set by company policy, insurers, contracts or industry rules (casinos, cannabis, banking). 30 days is common practice.