Free online tool
CCTV Storage and Retention Calculator
Find out how much storage your CCTV recorder needs to keep 30 days or more of footage, and check how many days your current recorder should hold.
About this tool
The SPS Technical CCTV Storage and Retention Calculator is a free online tool. It estimates the hard drive storage a CCTV recorder needs from the number of cameras, resolution (2MP to 8MP), scene activity, compression (H.265 or H.264), recording mode and the number of days of footage to keep, using typical bitrates for modern commercial IP cameras. For example, 8 x 4MP cameras recording continuously with H.265 for 30 days need about 6.5 TB, so an 8 TB recorder. It also shows how many days an existing recorder should hold. Results are estimates.
Designed for Facilities managers, estates teams, IT managers and business owners responsible for CCTV. SPS Technical provides commercial fire and security design, installation, maintenance and monitoring across Yorkshire, Lincolnshire and the Humber.
Start CCTV Storage and Retention Calculator
Enter your cameras, how busy each view is and how many days of footage you need. The estimate updates as you go. Add your recorder's current storage to see how many days it should hold.
Your cameras
Add a row for each mix of camera type. Not sure? The defaults suit most commercial sites.
We set systems to keep at least 30 days.
Your estimate
6.5 TB
to keep 30 days from 8 cameras, about 216 GB a day.
Suggested recorder storage
8 TB
Includes about 10% spare so the recorder never runs full.
Estimate only. Real storage depends on the cameras, their settings, lighting and how much movement there is. We confirm it at survey and check retention at every service.
Storage figures are estimates based on typical bitrates for modern commercial IP cameras and the settings you choose. Actual storage use depends on the camera model, settings, lighting and scene activity. It is not a survey or a guarantee of retention; SPS Technical confirms storage requirements at survey.
This tool provides an initial indication only. Results are based on the information you have provided and recognised industry standards. They are not a substitute for a site-specific technical assessment, insurer advice or formal compliance review. Maintenance requirements may vary depending on system type, site conditions, monitoring arrangements, certification status and insurer requirements. SPS Technical can confirm the correct requirements following a review of your system.
How Much Storage Does CCTV Need? Worked Examples
These examples use H.265 compression, recording all the time, with typical commercial settings:
- 4 × 4MP cameras, normal views, 30 days: about 3.2 TB, so a 4 TB recorder.
- 8 × 4MP cameras, normal views, 30 days: about 6.5 TB, so an 8 TB recorder.
- 16 × 5MP cameras, normal views, 30 days: about 16 TB, so a 20 TB recorder.
- 32 × 4MP cameras, busy views, 31 days: about 43 TB, so a 48 TB recorder.
Each camera recording all the time at 4MP uses roughly 25 to 30 GB a day. Busy views, such as car parks and roads, can use 50% or more extra. Older H.264 recorders need almost twice as much space as H.265.
How Long Should CCTV Footage Be Kept?
There is no single legal period. Under UK GDPR you should keep footage only as long as you need it for the purpose you recorded it for, and the ICO expects you to be able to explain your choice. For most businesses, 30 days is a sensible balance: long enough for an incident to be noticed and footage retrieved, short enough to limit the personal data you hold.
SPS Technical sets systems to keep at least 30 days of footage, and up to 45 days where a site needs it. Some insurers, contracts or sector rules ask for a specific period, so check yours.
What Affects How Much Storage You Need
Resolution. More pixels means more data. An 8MP (4K) camera uses roughly twice the storage of a 4MP camera.
Movement in the scene. Cameras compress still scenes very efficiently. Trees, traffic, rain and busy entrances all add data.
Compression. H.265 needs roughly half the space of the older H.264.
Recording mode. Recording only on motion or events can cut storage sharply, but you may lose footage just before or after an incident. Most commercial sites record all the time.
Night time. Infrared images can be noisier and use more data, especially with cheaper cameras.
Why Your Recorder Might Keep Fewer Days Than Expected
If you can't get footage back as far as you expect, common causes are extra cameras added to the same recorder, settings changed to higher resolution or frame rate, a failed hard drive, or a recorder that was never sized for the period you need.
Our CCTV maintenance checks retention at every visit, and remote health monitoring checks every hour that each camera is recording. The free CCTV Health Check compares the footage you need with what you can actually retrieve.
CCTV Storage and Retention Calculator FAQs
How many days of CCTV footage should I keep?
There is no fixed legal period. Keep footage only as long as you need it and be able to explain why. Thirty days suits most businesses. SPS Technical sets systems to keep at least 30 days, and up to 45 where a site needs it.
How much storage does one CCTV camera use?
A 4MP camera recording all the time with H.265 compression typically uses around 25 to 30 GB a day, or roughly 0.8 TB a month. Busy scenes and older H.264 recorders use more.
Does recording on motion save storage?
Yes, often by half or more, depending on how much happens in the view. The trade-off is that you may miss the moments just before or after an event, so most commercial sites record all the time.
Is this calculator accurate?
It gives a realistic estimate based on typical bitrates for modern commercial cameras. Real figures vary with the camera model, settings and scene, so we confirm storage at survey.
Can you upgrade the storage in my existing recorder?
Often, yes. Many recorders have spare drive bays or can take larger drives. We check what your recorder supports and whether a new recorder is better value.
Want a Professional to Verify Your Findings?
Complete the tool above, then request a professional review from SPS Technical. We can confirm the findings on site and explain any remedial options.