Choose the reason for keeping footage before choosing a storage capacity. Your retention target should support the purpose of the system and how incidents are identified, while avoiding unnecessary retention. A larger hard drive is not, on its own, a reason to keep recordings longer.
Is there a fixed UK retention period?
UK data protection law does not prescribe one minimum or maximum retention period for every CCTV system. The ICO says retention should follow the purpose of recording and that organisations should document and check their policy. See the ICO's guidance on surveillance and retention. This page explains system planning; your organisation should decide its policy with the person responsible for data protection.
Work backwards from the requirement
Once a justified retention target is agreed, estimate the recorded data. Camera count, average bitrate, frame rate, scene activity and recording schedules affect capacity. A quiet office on motion recording may behave differently from a busy yard. Measurements from the configured system are more useful than a camera's maximum advertised bitrate.
Continuous and motion recording
Continuous recording is easier to estimate because the cameras record for the full period. Motion recording varies with the scene and detection settings. Rain, trees, headlights and regular activity can trigger more recording than expected. Do not size a system on optimistic motion savings without allowing for busy periods and checking the result.
Check what the recorder actually holds
After commissioning, allow enough time for the system to build a recording history, then check the oldest available footage across the cameras. Confirm timestamps and test playback at different times. Changing the quality setting or adding a camera can shorten retention even if the storage has not changed.
Preserve an incident separately
An important clip can be overwritten by normal recording if it is left on a rolling recorder. Establish an authorised export process and secure handling for clips that need to be retained for a particular incident. Decisions about access and longer retention should follow the organisation's policy and the circumstances.
Estimate capacity and plan servicing
Use our storage calculator to see the effect of bitrate, cameras and days. It estimates raw recording data, not guaranteed recorder capacity. Our maintenance service can check recording history, disk health and whether settings still match the intended operation.