How many days of footage should you keep

The question isn't technical, it's about your business

The real question isn't “how much storage can I afford,” it's “how long does it usually take before someone notices the loss and asks for the footage.” The answer sets the retention window, and the retention window is what sizes the disk — not the other way round.

Typical windows by business type

In a shop that's usually 15 to 30 days — enough for a customer or staff member to notice and report something from those two to four weeks. In a warehouse the period is different: usually one full stocktake cycle, because a shortfall is found when the count is done, not on the day it happened.

These two examples aren't a rule for every site — the length depends on how quickly that particular business usually notices something is missing.

What that costs in storage

As a rough figure, 6 GB per camera per day at 4 MP, 15 fps and H.265 — nine cameras over thirty days comes to about 1.6 TB. The same nine cameras at 15 days cuts that number in half, and at 60 days doubles it.

Storage is cheaper than a second call-out for an undersized disk, but buying more storage than the business reason calls for is money spent without one.

H.265 vs H.264: why compression changes the budget

H.265 stores the same picture in roughly half the space of the older H.264, at the same resolution and frame rate. For a system of around ten cameras, that's the difference between one drive and two in the recorder — often enough to stay within a single unit instead of needing two.

Recommendation and the legal minimum

Set the retention window by purpose, not by however much disk fits in the recorder — keeping footage longer than needed carries its own liability, covered in more detail in the article on footage and the law. The camera and storage calculator takes a camera count and a target number of days and returns a starting disk size; the final choice of recorder and drives is made on site.