Hikvision DS-2DE4425IW-DE(T5) 4MP PTZ — storage & retention

The DS-2DE4425IW-DE(T5) is a 4MP 25x PTZ, and its 4MP sensor is the single biggest storage driver in this preset. At a typical 16 Mbps encode rate and 25 fps using H.265+, one camera writes roughly 173 GB per day of continuous footage. H.265+ is a smart, scene-adaptive codec — it lowers bitrate during static scenes and only spends bits where motion actually happens, so the same 4MP image at 16 Mbps would need a substantially larger allocation under plain H.264 to hold equivalent detail. That codec efficiency is what keeps 173 GB/camera/day realistic rather than the 260-300 GB/day a less efficient codec would demand at this resolution and frame rate.

Scaling from a single camera to a fleet is linear: 16 cameras recording continuously for 30 days multiplies out to approximately 83 TB of raw storage. Push retention to 60 or 90 days, or add more PTZ units to the same site, and the figure scales proportionally — double the cameras or double the retention window and the storage requirement doubles again. At 16 cameras, the resulting head-end sits comfortably in the Entry NVR class; larger fleets or longer retention windows on this camera would step the architecture up to a mid-tier or distributed-storage class well before reaching 90 days at the same count.

To use the calculator for this model, drag the camera-count slider and the retention-days input to match your actual site, and toggle the recording schedule between continuous and motion-triggered to see the effect immediately. A motion-only schedule applies a duty-cycle factor to the 173 GB/camera/day baseline, since a PTZ patrolling a mostly static scene spends much of its time on low-bitrate frames — the calculator recomputes the total storage and the implied NVR class the moment any of these values change.

What the calculator does not decide: real scene activity varies the H.265+ bitrate well outside a fixed 16 Mbps average — a busy scene with constant PTZ movement will write more than a static one even on the same schedule setting. It also does not add RAID or redundancy overhead, does not select a failover or long-term archive tier, does not check whether the network and switch can sustain the aggregate write throughput of the fleet, and does not specify an exact drive count, capacity, or model. Those remain engineering decisions for the actual site design.