Security Advice · CCTV
How Long Does CCTV Footage Actually Last?
Everybody asks how many cameras and almost nobody asks how many days. It is the same question – your recorder overwrites the oldest footage to make room, so storage is simply how far back you can see.
The short answer
- A recorder overwrites the oldest footage when it fills. That loop length is your real retention.
- 4 × 4MP cameras recording continuously fill 1TB in about six days.
- 8 × 4K cameras fill 2TB in about three days. This is the one that catches people out.
- Recording on motion rather than continuously typically doubles or triples the days you keep.
- If something happens, export the clip immediately. Do not assume it will still be there next week.
How a recorder actually behaves
An NVR writes continuously to a hard drive. When the drive is full it does not stop and it does not warn you – it starts overwriting the oldest recording. That is correct behaviour, and it means your system has a rolling window: everything inside it is available, everything before it is gone permanently.
So “how long does footage last” is not a setting. It is arithmetic: how much video you generate per day, divided into how much drive you bought.
The uncomfortable part is that nobody discovers their window is three days until the day they need day four.
The arithmetic, with real numbers
A camera’s storage use is set by its bitrate – roughly 4 Mbps for a 4MP camera on a modern codec, roughly 8 Mbps for 4K. One camera at 4 Mbps writes about 42 GB a day. Multiply by cameras, divide into the drive.
| System | Recording mode | 1 TB | 2 TB | 4 TB |
|---|---|---|---|---|
| 4 × 4MP | Continuous | ~6 days | ~12 days | ~24 days |
| 4 × 4MP | Motion only | ~14 days | ~28 days | ~8 weeks |
| 8 × 4K | Continuous | ~1.5 days | ~3 days | ~6 days |
| 8 × 4K | Motion only | ~4 days | ~7 days | ~2 weeks |
| 6 × 5MP | Motion with pre-buffer | ~7 days | ~14 days | ~4 weeks |
The 4K row is the one worth staring at. A well-specified eight-camera 4K system on the 2TB drive it usually ships with holds about three days if it records everything. That is not a fault – it is what 4K costs in storage – but it is a decision, and it should be made at the quote rather than discovered in March.
It is also why the storage line on a what CCTV costs installed quote is worth more attention than the camera line. A larger drive is one of the cheapest upgrades available and the only one that changes what you can look back at.
Three ways to buy more days
Record on motion, with a pre-buffer
The biggest single gain. Most of the day, most cameras are looking at nothing happening. Recording only when something moves typically doubles or triples the window.
The catch is the beginning of an event. A camera that starts recording when motion trips has already missed the approach. Any decent recorder can hold a rolling few seconds and write them in front of the trigger – a pre-record buffer – so the clip starts before the person entered frame. Turn it on. A motion clip without it frequently starts with someone already at the door with their back to you.
Set the schedule to match the risk, per camera
The driveway camera can record continuously through the night and on motion during the day. An indoor camera can be off entirely while the alarm is disarmed and someone is home. Per-camera schedules are the difference between a system sized for its busiest hour and one sized for its average.
Buy the bigger drive at install
Going from 2TB to 4TB is a modest cost at the point of installation and doubles your window forever. Doing the same thing later means opening the recorder, and on some systems reinitialising it – which wipes what is on there.
The mistake that costs people the footage
The single most common way people lose the clip they need is not a technical fault. It is delay.
Something happens, they check the footage, they see it is there, and they leave it – meaning to deal with it once they have spoken to the insurer or the police. Ten days later, on a three-day loop, it is gone. The system worked exactly as designed.
If something happens, export the clip that day. Every app has a save or download button. Put the file somewhere that is not the recorder – your phone, a cloud drive, an email to yourself.
Export more than you think you need: an hour either side, and every camera that saw anything, not just the obvious one. It costs nothing and you cannot go back for it later.
If a system is professionally alarm monitoring, there is a second copy of the important part – operators pull and retain footage attached to a verified event. For a commercial site that alone is often worth the monthly fee.
How long should you keep footage?
For a home, one to four weeks is the sensible target. It covers the realistic gap between something happening and you noticing – the shed you did not visit for a fortnight, the fence damage you spotted on the weekend.
For a business there is a second consideration: under the Privacy Act you should not keep personal information longer than you need it for the purpose you collected it. In practice that means picking a retention period, documenting it, and letting the loop do its job – not hoarding a year of footage because the drive was cheap. There is more on that in the privacy rules on CCTV in NZ.
Thirty days is a common commercial default and a reasonable one. Sizing a system to hit it deliberately is a different exercise from hoping the drive that came in the box is enough.
Common questions
How many days of CCTV can a 1TB recorder hold?
Roughly six days for four 4MP cameras recording continuously, or about two weeks on motion-only recording. Four 4K cameras on the same drive would manage around three days continuous.
How long do most CCTV systems keep footage?
Between three days and a month, depending entirely on camera count, resolution and whether they record continuously. Most homes we set up run a rolling one to four weeks.
Does CCTV footage delete itself automatically?
Yes. When the drive is full the recorder overwrites the oldest footage. There is no warning and no way to recover what has been overwritten, which is why you should export anything important on the day.
Is 2TB enough for an 8-camera system?
Only for a few days if the cameras are 4K and recording continuously – about three. With motion recording and a pre-buffer it stretches to a week or so. If you want thirty days on eight 4K cameras, plan for a much larger drive at install.
Should CCTV record continuously or on motion?
Motion recording with a pre-record buffer suits most homes and multiplies the days you keep. Continuous recording is worth it on high-value commercial sites and on the one or two cameras where missing anything is unacceptable.
Can deleted CCTV footage be recovered?
Realistically, no. Once the recorder has overwritten that part of the drive it is gone. Treat anything you might need as something to export immediately rather than something to come back to.
Want to know how far back your system can see?
We size storage to the days you actually want, not to whatever drive came in the box. Free assessment across Auckland.