The formula that settles everything
Archive volume is simple: camera bitrate (Mbps) ÷ 8 × 86,400 ÷ 1,000 = gigabytes per day per camera (86,400 being the seconds in a day). A 4 MP camera with H.265 in a typical scene writes 2–4 Mbps — that is 20–45 GB a day.
Then multiply by cameras and days of storage. A 3 Mbps stream is 32.4 GB a day; eight such cameras for 30 days: 32.4 × 8 × 30 ≈ 7.8 TB. So an 8 TB drive is borderline — take 10 TB or two eights.
What drives the bitrate most
The codec: H.265 saves up to half the volume versus H.264 — enable it wherever the recorder supports it. Motion in frame: a camera over a busy checkout writes twice as much as one in a quiet corridor. Night: sensor noise inflates the stream, so outdoor cameras are 'heavier' at night.
Smart codecs (H.265+) add savings on static scenes, but bake them into the calculation cautiously: a live site can be noisier than the vendor's calculator promises.
A table of typical configurations
A home, four 2 MP cameras, 14 days — about 1 TB: a 2 TB drive is fine. An office, eight 4 MP, 30 days — 6–8 TB: an 8–10 TB drive. A store, sixteen 4 MP, 30 days — 12–16 TB: two 8–10 TB drives. A warehouse, 32 cameras, 30 days — 25–35 TB: a four-bay recorder or server storage with RAID.
The headroom rule is plus 20–25%: real bitrate always beats the calculator, and a circular archive must never run to zero free space.
Why a desktop drive will not do
CCTV writes 24/7 — a regime desktop drives were not designed for: they expect an office's eight hours with pauses. In a recorder such a drive lives a year or so and dies together with the archive.
Surveillance series — WD Purple, Seagate SkyHawk — are built for round-the-clock recording of dozens of streams and the vibration of neighboring drives, with DVR/NVR-tuned firmware. The price difference is about fifteen percent; the endurance difference is multiples.
When one drive is not enough
From 16 cameras or archives beyond a month, look at recorders with two to four bays: the volume adds up and each drive works easier. For critical sites — RAID storage: a failed drive does not take the archive with it.
And keep a free bay: growing the archive is the most common post-launch upgrade, and a spare bay is the cheapest way to prepare for it.
We will do the math for you
Our online calculator gives the ballpark for a whole system, and an engineer will size it exactly for your cameras, scenes and retention — free. WD Purple and Seagate SkyHawk drives of all popular sizes are in stock in Tashkent, with warranty.
If the archive no longer fits — we come, check the bitrates and either tune the codecs or size a storage upgrade. A month of archive often comes back with one settings fix.
FAQ
How long must recordings be kept by law?
There is no single norm for private sites — the owner or industry requirements set the term (banks and malls have their own). The practical business standard is 30 days.
Does motion-triggered recording save much space?
Yes, on quiet sites — several times over. But for checkouts, warehouses and client disputes continuous recording is safer: detection can miss the start of an event.
Can I use an SSD?
For circular video recording an SSD is not economical: write endurance burns fast and the speed is not needed. SSDs fit the system/analytics; the archive belongs on surveillance-class HDDs.
Installation works cost calculator
Set the number of points — the calculator lays out a site plan and shows the range from our standard price list. One minute, no phone calls.
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