Security cameras · storage
CCTV storage calculator.
Enter cameras, bitrate, retention days and the share of the day recorded to see the terabytes of disk you need.
Inputs
Disk needed
Enter the numbers above.
How much storage does a CCTV system need?
Storage is bitrate multiplied by time. A camera that streams at 4 Mbps writes 0.5 megabytes every second, so one day of continuous recording is 0.5 MB x 86,400 s = 43.2 GB. Multiply by the number of cameras and the retention days, then add a margin so the disk is never completely full. Choosing a share below 100 percent models motion-only recording; the tool multiplies the recording time by that share. Disk makers count a terabyte as 10^12 bytes, so the tool reports TB and also TiB (2^40 bytes), the unit many operating systems show.
Worked example. 8 cameras at 4 Mbps for 30 days of continuous recording is 8 x 43.2 GB x 30 = 10.37 TB. A 10 percent margin makes it 11.40 TB, which is 10.37 TiB. At 30 percent motion recording the same system needs 3.42 TB.
The bitrate you enter should come from your camera or recorder settings, because real streams change with scene activity, night noise and the codec. Check the actual rate the recorder reports after a few days.
Frequently asked questions
How much storage does one IP camera use per day?
A camera streaming at 4 Mbps uses 43.2 GB per day of continuous recording, and one at 2 Mbps uses 21.6 GB. The tool multiplies your bitrate by 86,400 seconds and divides by 8 to get bytes.
How many terabytes for 4 cameras at 2 Mbps for 30 days?
With the margin set to 0 and continuous recording, 4 cameras at 2 Mbps for 30 days need 2.59 TB.
Does motion recording reduce storage?
Yes, in proportion to how much of the day the cameras actually record. If they record 30 percent of the time, storage is about 30 percent of continuous, plus any pre- and post-event buffers you add to the share.
Why is my disk showing less than the advertised TB?
Drive makers use decimal units where 1 TB is 10^12 bytes, while many operating systems report binary units, so the same disk shows a smaller number. Formatting and recorder overhead take a little more.
Sources
Checked
- Wikipedia, "Gigabyte", opened 8 October 2026. IEC 80000-13: a gigabyte (GB) is 10^9 bytes, a gibibyte (GiB) is 2^30 bytes
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Scope
Planning arithmetic only. It is not a security design and does not confirm legal compliance; recording and privacy rules vary by place. Bitrate, margin and recording share are your inputs; this is a planning estimate, not a guarantee of retention.