How Much Storage Do You Need for Security Cameras? (2026 Sizing Guide)

Multiply cameras by daily write rate by retention days. As a working guide allow 8-15 GB per day for an HD camera, 15-25 GB for 2K and 30-50 GB for 4K on continuous recording. Ten 4K cameras kept 30 days needs roughly 12 TB of usable footage capacity, before RAID overhead. Retention and recording mode change this more than anything else.

Roughly 30-50 GB per day on continuous recording, though the range is wide because frame rate, scene activity, compression and lighting all matter. A camera watching a busy road at 30 fps sits at the top of that range or above; a quiet stockroom at 15 fps sits well below it. Infrared night footage often costs more than daytime because image noise compresses poorly.

Common practice is 7-14 days for homes and small shops, 30 days as the usual business default, and 60-90 days where insurance requirements or slow-surfacing disputes apply. Retention can also be set by your insurer, industry body, licensing conditions or contracts - and privacy considerations cut the other way, since keeping footage longer than needed carries its own obligations. Confirm what applies to your organisation.

Yes - motion-triggered recording commonly uses 30-50% of continuous, and smart detection filtering for people or vehicles less again. The trade-off is that you may miss the moments before a trigger, and weather can cause false triggers. Most professional installations record continuously on cameras that matter - entrances, tills, gates - and use detection-based recording elsewhere.

Raw is the sum of the drives; usable is what remains after redundancy. Single parity gives roughly (n-1)/n of raw, two parity drives roughly (n-2)/n, and mirroring halves it. For example, sixteen 18 TB drives is 288 TB raw but around 252 TB usable with two parity drives. Always size your retention against the usable figure.

Yes. Surveillance drives are designed for continuous write loads and for multiple drives vibrating together in one chassis. Desktop drives are built for intermittent use and fail significantly earlier in this duty - a false economy on a system whose purpose is to have the footage when you need it.

Fewer, larger drives. Bay count is fixed when you buy the recorder, but drive size is the only thing you can increase later. Filling every bay with small disks means the only way to expand is replacing all of them. Buy the largest drives your budget allows and leave bays free where possible.

Generally no - UniFi Protect recorders ship with empty bays, and drives are a separate purchase. Check the manufacturer's storage compatibility list before ordering, because compatibility is physical as well as electronic: some drives lack the mounting screw positions the caddies expect.

You can fill empty bays, and you can replace drives with larger ones, though replacing drives in a protected array is a staged process rather than a swap. What you cannot change is the number of bays - which is why bay count, not initial drive size, is the specification to get right at purchase.

Yes. Ubiquiti publishes a capacity calculator at calculator.ui.com where you enter camera counts by resolution, intended drive size and target retention, and it reports how many drives you need - covering gateways that record as well as dedicated recorders. Use it to sanity-check any estimate you build by hand.

Yes, close to linearly. Halving frame rate from 30 to 15 fps roughly halves storage. For most evidence purposes 15 fps is entirely adequate - you are identifying people and events, not analysing motion - so it is one of the easiest savings available on cameras where fluid video is not required.

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Use a surveillance-rated CMR drive. For a home or small business NVR, WD Purple or Seagate SkyHawk suits most systems: both are rated for 180TB/year of workload with a 3-year limited warranty. For AI-enabled recorders, video management servers or large multi-bay systems, step up to WD Purple Pro or Seagate SkyHawk AI, which are rated for 550TB/year with a 5-year limited warranty.

Work out usable storage first (cameras x daily write rate x retention days, plus RAID overhead), then divide by the number of bays. As a guide, a 4-8 camera home NVR typically uses 2-8 TB drives, a small business system with 8-16 cameras 6-8 TB or larger, and AI or VMS systems 8 TB and up. WD publishes its rating of up to 64 HD cameras for WD Purple at 6TB and larger.