Dahua DH-IPC-HFW2431S-S-S2 (4MP) — storage & retention

The DH-IPC-HFW2431S-S-S2 is a 4MP sensor running H.265 at a typical 6 Mbps at 30 fps, and that bitrate is the single largest driver of the storage figure: roughly 65 GB per camera per day at continuous recording. H.265's smart-codec efficiency is doing real work here — the same 4MP feed on plain H.264 would typically run meaningfully higher in bitrate for equivalent picture quality, which is why H.265 support is usually the first spec line to confirm on a 4MP camera before storage is even discussed.

Scaling from one camera to a fleet is linear: 16 cameras at ~65 GB/camera/day over a 30-day retention window multiplies out to roughly 31 TB. Double the retention to 60 days and the figure roughly doubles; add cameras and it scales the same way. At 16 cameras and this bitrate profile, the recording head-end falls into the Entry NVR class — a step above a single-bay budget recorder but well short of the multi-bay arrays that 32+ camera fleets or longer retention windows require.

To use the calculator for this camera: the camera count, retention window and recording schedule are already set to the 16-camera, 30-day, continuous-recording defaults above. Drag the camera-count or retention sliders to see the storage figure recompute in real time, and switch the schedule to a motion-only profile to see how a duty factor (typically well under 100% active recording time) reduces the total against the always-on baseline.

What the calculator does not decide: it uses a scene-average bitrate assumption and cannot account for real-world variance from high-motion scenes, low-light IR activation, or compression complexity on any given camera. It does not add RAID or redundancy overhead, does not plan a failover or archive tier, does not check the recording head-end's network write throughput against the aggregate camera bitrate, and does not produce an exact drive count or model — those remain a BOQ-level decision for the recording architecture.