Retention
Camera storage and retention calculator
Two directions: how many days your existing storage holds, or how much storage a target retention needs. You supply the bitrate from your own camera documentation, because there is no honest generic figure and we are not going to invent one.
Both directions
Days from storage, or storage from days
Nothing you enter leaves your browser. There is no submission and no storage of these figures.
Enter a bitrate and the result appears here. JavaScript is required for this panel; the rest of the page works without it.
Every assumption this tool makes
- Bitrate is yours, not ours. We bake in no figure. A generic bitrate is a capability spec for a product we have not seen at a setting we did not choose, and publishing one would be a fabricated number.
- Megabits are divided by 8 to get megabytes. Manufacturers quote bitrate in Mbps and storage in TB, and mixing the two is the commonest error in this calculation.
- Storage uses decimal TB (1012 bytes), which is how drives are sold. A formatted drive presents less than its label, and any redundancy reduces usable capacity further.
- The result is an estimate and it will drift. Modern encoding produces less data from a still scene than a busy one, so a camera on a quiet corridor and an identical camera on a loading bay do not consume the same storage.
- It assumes every camera runs at the same bitrate. Where yours differ, run the busiest group separately instead of averaging.
- It recommends no product, states no price, and does not tell you what to buy.
Why the bitrate field is empty
Every other calculator fills this in. That is the problem
The number a storage calculator assumes is the number that determines its answer, and it is almost always invisible to the person using it.
Bitrate is not a property of cameras in general. It is a property of a specific camera, at a specific resolution and frame rate, using a specific encoder, pointed at a specific scene. Change the scene and it changes. A calculator that quietly assumes a figure is not saving you a step; it is making the most consequential decision in the calculation on your behalf and not telling you what it chose.
We do not publish capability figures we have not verified for the product in question, and a calculator is not a loophole in that rule. It is the worst place to break it, because the assumption disappears into an output that looks like a measurement.
Finding your real figure is easier than it sounds. Most commercial cameras publish a bitrate range in the datasheet for each resolution and frame rate combination. Better still, most recorders display the actual per-channel bitrate they are receiving right now, which is your own equipment watching your own scenes and is the best number available to anybody.
What actually moves the answer
Four inputs, and three of them drift after handover
The retention figure quoted at handover describes the system as it was configured on that day. Nothing keeps it true, and no system announces that it has changed.
- Camera count. The one that drifts most, because it drifts by addition. Every camera added after handover divides the same disk further. A building that expands or takes an adjacent suite usually adds cameras without anybody revisiting the window.
- Resolution and frame rate. Both multiply the data a camera produces. Higher is not automatically better: a view whose job is to show that a door opened does not need what a view whose job is to identify a face needs, and setting everything to the maximum is how a retention window quietly halves.
- Scene activity. The one nobody predicts, and the reason this tool calls its output an estimate. Change what happens in front of a camera and its consumption changes with it.
- Usable capacity. Not the sum of the drives. Formatting takes some, and any redundancy takes more.
The wider version of this, including how to check what your system is actually holding right now, not what it was specified to hold, is in how long do security cameras keep footage.
The one legal number
Where retention is fixed for you, not chosen
For most commercial premises in California there is no statute setting a retention period for your own camera system. The clearest exception is cannabis. The Department of Cannabis Control's regulations, at California Code of Regulations, title 4, section 15044, require a licensed premises to retain recordings for a minimum of 90 calendar days, and require recording to run continuously, 24 hours a day. That combination is what makes the storage question serious: 90 days of continuous recording is a very different figure from 90 days of event clips.
Verified as of 25 August 2026. Regulations change; check the current text before you rely on it. The full set of obligations is on dispensary and cannabis security, there is a dated summary in our free resources, and the readiness check is at the § 15044 checker.
Otherwise the period is set by your own policy, your insurer or your parent company. If one of those specifies a figure, that figure is the design input and we build to it. We are not going to tell you what your policy says.
Two boundaries, as on every page here. We work on commercial premises only and not on private residences. And we do not hold a C-10 or a C-16, so we do not work on fire alarm systems; that is coordinated with your own licensed fire alarm contractor.
How storage is sized as part of a whole design is under commercial camera installation, and checking an existing system against what it was supposed to be doing is CCTV service and repair.