How Much Storage Do You Need for CCTV?

The amount of CCTV storage you need depends on the number of cameras, their resolution, the compression format used, your recording mode, and how many days of footage you are required to retain. For most commercial sites recording continuously in 1080p with H.265 compression, a practical starting point is 1TB per four cameras for 31 days of retention. In practice, the figure varies considerably, and sizing storage correctly from the outset is one of the most important decisions in any commercial CCTV installation.

This article explains what drives storage requirements, how to calculate the right capacity for your site, what UK guidance says about retention periods, and how your choice of storage type affects the overall system.

What Affects How Much Storage a CCTV System Needs

CCTV storage requirements are not fixed. They are the product of several interacting variables, and changing any one of them can shift your total storage figure substantially. The five factors that have the greatest impact are:

• Camera resolution determines how much data each camera generates per second. A 1080p camera produces significantly less data than a 4MP or 4K camera capturing the same scene. Upgrading resolution without reviewing storage capacity is one of the most common causes of premature NVR overrun on systems that were not re-specified at the time of the upgrade.
• Compression format controls how efficiently raw video data is encoded before it is stored. H.265 (also called HEVC) typically reduces file sizes by around 50% compared with the older H.264 standard, at equivalent image quality. H.265 has become the default for most modern commercial CCTV systems and NVRs, and selecting a system that supports it is one of the most straightforward ways to control storage costs.
• Frames per second (FPS) affects both the smoothness of recorded video and the volume of data generated. Standard real-time recording runs at 25fps in the UK. Reducing to 12fps halves the data volume and is often acceptable for perimeter or low-movement zones where identifying individuals or vehicles is the primary goal rather than capturing fluid motion.
• Recording mode is the single biggest lever on storage size. A camera recording continuously 24 hours a day generates far more data than the same camera set to record only when motion is detected. For active commercial sites with consistent footfall, continuous recording is usually necessary to maintain evidential integrity. For lower-traffic areas such as external perimeters or car parks during off-peak hours, motion-triggered recording can reduce storage requirements by 60-80%.
• Camera count and retention period scale storage linearly. Doubling the number of cameras doubles the storage required. Extending the retention period from 14 days to 31 days increases storage proportionally. Both decisions need to be factored into system specification before hardware is purchased.

How to Calculate CCTV Storage Requirements

The Storage Calculation Formula

The standard formula for calculating CCTV storage is:

Storage (GB) = Bitrate (Kbps) x 1,000/8 x 3,600 x 24 x number of cameras x days / 1,000,000,000

Breaking this down:

• Bitrate is the data output of each camera in kilobits per second (Kbps). This is set in the camera or NVR configuration and is directly linked to resolution and compression settings. A typical 1080p H.265 camera runs at 1,000–2,000 Kbps. A 4K camera may run at 4,000–8,000 Kbps.
• The 1,000/8 conversion converts kilobits to kilobytes.
• The 3,600 x 24 converts the per-second figure to a daily total.
• Multiplying by camera count gives the daily site total.
• Multiplying by days gives the total storage required for the retention period.
• Dividing by 1,000,000,000 converts bytes to gigabytes.

Worked Examples for Common Commercial Setups

The table below shows indicative storage requirements for three typical commercial configurations, all using H.265 compression and continuous recording over a 31-day period.

These figures are indicative. Real-world storage consumption varies with scene complexity, lighting conditions, motion levels and the specific camera models installed. A professional CCTV system design should always include a 20-30% headroom allowance above the calculated minimum to accommodate variance and avoid footage being overwritten ahead of schedule.

For sites using motion-triggered recording, total storage in active commercial environments typically falls to 30-50% of the continuous recording equivalent, though this depends on how much activity the cameras are monitoring.

When Clearway designs a commercial CCTV system, storage specification is calculated as part of the system design process rather than as a separate afterthought. The camera resolution, compression settings and recording schedules are configured to meet the client’s retention requirement within the chosen hardware budget, with headroom built in from the outset.

Daniel Meeajane

Business Development Director, Clearway
Clearway

Daniel Meeajane

Most businesses significantly underestimate their CCTV storage requirements when first installing a system — the combination of higher-resolution cameras, longer retention periods and multiple sites can push storage needs to levels that require purpose-built NVR solutions rather than basic consumer-grade drives.

Get a CCTV storage assessment for your site. Speak to the Clearway team.

How Long Does UK Law Require CCTV Footage to Be Kept?

CCTV storage planning in the UK cannot be separated from the legal framework governing how long footage may be held. Getting this wrong carries compliance risk under UK GDPR and ICO regulation.

The ICO states that CCTV footage should be retained for no longer than is necessary for the purpose for which it was recorded. In practice, the ICO’s own CCTV and surveillance guidance identifies 31 days as the typical maximum for general commercial use, after which footage should be overwritten or deleted unless there is a specific reason to extend retention, such as an ongoing investigation, an insurance claim or a formal legal hold.

UK GDPR’s data minimisation principle means that retaining footage indefinitely, or beyond the period necessary, creates legal exposure. Systems must be configured to overwrite on a schedule that reflects the stated retention policy, and that policy must be documented as part of the organisation’s wider data protection obligations.

For higher-risk environments, longer retention may be justified. Construction sites facing active theft or vandalism, for example, may retain footage for 60 or 90 days where incidents are under investigation and insurers or police require extended access. Any extension beyond the standard retention period should be documented with a clear rationale.

At the minimum end, while UK law does not mandate a minimum retention period, police and insurers typically advise a practical minimum of 28 days to ensure that footage relevant to reported incidents can be retrieved. A system configured to overwrite after 7 or 14 days risks losing footage before an incident is reported or investigated, which can affect insurance claims and police enquiries alike.

Local Storage vs Cloud Storage for Commercial CCTV Systems

The choice between local and cloud storage affects system cost, resilience and operational flexibility. For most commercial deployments, the decision is shaped by site type, camera count and whether remote access to footage is required.

Local storage via NVR or DVR is the most common approach for fixed commercial sites. An NVR (Network Video Recorder) or DVR (Digital Video Recorder) with sufficient internal hard drive capacity stores footage on-site. This approach keeps costs predictable, does not depend on internet bandwidth, and allows direct access to footage without cloud subscription fees. The limitation is that on-site storage is vulnerable to theft, fire or damage, and footage is only accessible from the physical location unless remote access is configured.

Cloud storage is increasingly used in combination with modern AI CCTV systems. Rather than uploading full-resolution continuous footage, which would require substantial bandwidth, AI-enabled systems such as Clearway’s inView Detect platform use on-device processing to identify events of interest and upload clips selectively. This reduces the bandwidth and cloud storage costs involved while maintaining a searchable, remotely accessible record of all flagged events. For multi-site operations where centralised oversight is a priority, this approach removes the need to manage separate NVR hardware at each location.

Remote CCTV monitoring removes much of the on-site storage burden entirely. Under a managed monitoring service, footage is assessed in real time at a professional monitoring centre. Recorded evidence of verified incidents is retained and managed by the monitoring provider. For organisations operating multiple sites, or sites with limited IT infrastructure, this model removes the complexity of specifying, maintaining and upgrading on-site NVR storage at each location.

Clearway’s NSI Gold accredited remote CCTV monitoring service provides 24/7 coverage with verified video response, reducing the dependence on local storage infrastructure while maintaining full evidential capability.

Sizing CCTV Storage Correctly

Sizing CCTV storage correctly is a system design decision, not an afterthought. The wrong specification leads either to footage being overwritten before it is needed, or to unnecessary cost from over-specifying hardware. The key variables (resolution, compression, recording mode, camera count and retention period) interact with each other, and changing any one of them affects the total.

For most commercial sites, a properly designed system running H.265 compression with motion-aware recording and a 31-day retention policy can be specified and maintained within a manageable budget. Where requirements are more complex, or where multi-site or high-risk environments are involved, professional system design from an experienced installer makes a significant difference.

To discuss your site’s CCTV storage requirements and get a professional assessment, contact the Clearway team at clearway.co.uk/contact.

Frequently Asked Questions

How many GB is enough for a CCTV camera?

The amount of storage needed per CCTV camera depends on the resolution, compression format, frames per second and recording mode configured on that camera. A single 1080p camera recording continuously with H.265 compression at 25fps uses approximately 15-20GB per day, meaning 1TB provides roughly 50-65 days of footage for that one camera. For higher-resolution cameras running at 4MP or 4K, the same 1TB may last only 15-30 days. Most commercial installations specify between 60GB and 300GB per camera per month depending on these settings.

How long will a 256GB SD card record on CCTV?

A 256GB SD card will record for approximately 2-4 days of continuous footage from a single 1080p camera, or up to 14 days or more if the camera is set to motion-triggered recording only. SD card storage is generally used for edge storage in standalone cameras or as a backup in locations where NVR connectivity is unavailable. For commercial systems requiring 28-31 days of retention across multiple cameras, an NVR with hard drive storage is the appropriate solution.

Is 2TB a lot of storage for security cameras?

2TB is a practical starting point for a small commercial system of 4-6 cameras recording in 1080p with H.265 compression over a 31-day period, but it is not sufficient for larger sites or higher-resolution cameras. For larger sites, or those running higher-resolution cameras, 2TB may only provide 7-14 days of footage. A 16-camera system at 1080p continuous recording with a 31-day retention target typically requires 8-12TB. Whether 2TB is sufficient depends entirely on the site’s specific configuration.

Is a 128GB SD card enough for CCTV?

A 128GB SD card is sufficient for a single camera used in a low-activity location with motion-triggered recording enabled, where continuous 24/7 recording is not required. For a commercial CCTV system requiring multi-day retention across multiple cameras, an NVR with dedicated hard drive storage is the correct specification. A 128GB SD card in a continuously recording 1080p camera would typically overwrite after 1-2 days, making it unsuitable as a primary storage medium for any professional security application.

Written by Daniel Meeajane

Business Development Director, Clearway Fire and Security

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Daniel Meeajane is Business Development Director at Clearway Fire and Security, bringing strong commercial expertise alongside a detailed understanding of fire protection systems and industry standards.

Having contributed to a number of major projects and delivered successful outcomes, Daniel uses his knowledge and experience to drive awareness of effective fire protection solutions across a wide range of environments. His approach combines relationship-led business development with a clear understanding of technical compliance, operational requirements, and customer risk.

Daniel has a strong understanding of BS 5839-1, recognising the importance of compliant fire detection and alarm system design, installation, commissioning, and maintenance. He also keeps pace with the latest developments in fire technology, ensuring clients benefit from informed guidance, up-to-date solutions, and best practice across every stage of delivery.