How long will your CCTV keep its recordings?

Understand what uses the storage

Recorded video consumes space according to its bitrate and how long it is recorded. Camera count adds to that total. Resolution, frame rate, compression and scene activity influence the bitrate, so two systems with the same advertised resolution can have different storage needs.

Axis’s storage guidance uses bitrate and retention time to size capacity. Treat a generic package estimate as a starting point and ask which settings it assumes. Usable drive capacity and recorder behaviour should also be included in the installer’s calculation.

Further reading: Axis: recording bitrate and storage capacity

Use a simple example to ask better questions

For illustration, one camera recording continuously at an average 4 megabits per second produces about 43.2 gigabytes of video per day: 4 ÷ 8 × 86,400 ÷ 1,000. Four cameras at that same average would produce about 172.8 GB per day.

On those simplified assumptions, 2,000 GB divided by 172.8 GB gives roughly 11.6 days, before filesystem overhead, reserved capacity, audio or other system differences. This is arithmetic, not a retention promise. Real video bitrates can vary, and the selected recorder should be checked with its actual settings.

Choose the recording schedule deliberately

Continuous recording preserves the timeline while recording is active. Event-based recording saves footage when the system detects a configured event. It may reduce storage use, but its usefulness depends on detection settings and what happens in the scene. Ask how time before and after an event is handled.

Walk through a realistic event during setup: someone approaches the gate, pauses and leaves. Review what was saved. If you need the surrounding context, make sure the recording policy captures it. Ask whether older footage is overwritten automatically and how storage faults are reported.

What changes the number of days your CCTV retains?

Retention depends on the amount of data recorded and the usable storage available. Camera count, configured bitrate, recording schedules and whether the system records continuously or on events all influence the result. The recorder's storage arrangement and reserved space can also affect the usable capacity.

Ask for an estimate based on the proposed settings, then verify it against the installed system. A simple statement such as 'two terabytes stores a month' leaves too many assumptions unstated. Two systems with the same drive size can retain different amounts of footage. Record the settings used for the estimate so any later change in image quality or recording schedule prompts another retention check.

Should CCTV record continuously or only on events?

Choose according to what you need to review and how the system detects activity. Continuous recording keeps a timeline across the configured recording periods. Event recording depends on the system recognising the configured trigger and capturing the relevant interval. Both approaches need practical testing.

Ask how the recorder handles activity before and after an event, and what happens if a trigger is missed or configured poorly. Review a person walking through each important view rather than assuming an event icon guarantees a useful clip. A mixture of schedules may suit some installations. The appropriate arrangement should be agreed around the purpose of each camera and the retention period you want to assess.

What happens when the recorder's storage fills up?

Many CCTV systems can be configured to overwrite older footage, but the exact behaviour depends on the recorder and its settings. Confirm the operating mode in the system documentation and at handover. Do not assume that a live picture means recordings are being retained or that old clips will remain indefinitely.

Learn how to locate the oldest available footage and check it periodically. If the retained period becomes shorter, investigate settings, camera additions and storage health. Export important authorised footage promptly using the supported process and confirm the exported file plays correctly. Keeping an event marked in an app may not be equivalent to preserving an independent copy, so ask what the feature actually does on your system.

How can you check that recordings are usable?

Create a simple test event at a known time, then locate it in playback. Check the camera name, timestamp, image and duration. Export the clip and open it on the device you expect to use for reviewing or sharing it. Some systems require a particular export format or player.

Repeat representative checks after settings changes or equipment replacement. Confirm who receives storage or recording alerts and what action they should take. Keep account access and exported footage managed appropriately for the people who need them. A handover that covers recording, search and export is more useful than a demonstration limited to live camera views, because the value of a recording system depends on being able to retrieve the relevant footage later.

Should you reduce image quality to keep more footage?

Only after considering what detail the camera needs to capture. A longer recording history is less useful if the saved footage no longer serves its intended purpose. Ask the installer to explain the trade-off between recording settings, usable image detail and retention for each important view.

Compare representative clips before accepting a change, including movement and the lighting conditions that matter at the property. Keep the previous settings recorded so the result can be assessed clearly. If the desired detail and retention cannot both be achieved with the available storage, discuss the appropriate system options. Avoid treating a lower setting as a free improvement when it changes the information preserved in every recording.

Practise finding and exporting a clip

A live image is only one part of the system. At handover, find an event by date and time, export it and confirm that the exported file plays on an appropriate device. Save important footage before the rolling recording period reaches it. Check timestamps so later searches are less confusing.

Remote access and local recording are separate functions. Ask how the selected system behaves if internet access fails and what needs power to keep recording. Use separate authorised accounts where supported and maintain updates and strong credentials, following the manufacturer’s instructions.

• Required number of days and the settings used to estimate it
• Continuous or event recording, including pre-event coverage
• Storage health alerts and overwrite behaviour
• A working export, correct timestamp and documented access settings

Further reading: Australian Cyber Security Centre: Internet of Things devices