An NVR is the easiest part of a CCTV order to get wrong, because the mistake only shows up after installation: cameras that record at reduced quality, a PoE budget that cannot power the last camera, or a hard drive that overwrites footage after six days. This guide covers the four numbers to check before you buy — with the recorder we would actually quote at each size.
1. Channels — buy headroom, not just today's cameras
The channel count is the maximum number of cameras the recorder accepts. The rule installers use: take the cameras on the plan and add at least 25% headroom. A site with 6 cameras belongs on an 8-channel NVR; a site with 10–12 belongs on a 16-channel. Adding a camera later is a ten-minute job when there is a spare channel, and a recorder replacement when there is not.
2. PoE budget — the number the spec sheet hides
Most NVRs with built-in PoE quote a total power budget (for example 130 W across 16 ports). A fixed dome typically draws 5–7 W, but a PTZ with infra-red can draw 20–25 W. Add up the real draw of the cameras you are fitting — not the port count — and leave 20% spare. If the budget is tight, power PTZs from a separate PoE injector.
3. Storage — days of retention, not just terabytes
A 4K (8MP) camera at 15 fps produces roughly 40–60 GB per day on continuous recording. Eight of them fill a 4 TB drive in under two weeks. Motion-triggered recording typically cuts that by 60–80%, which is why the same drive can cover a month on a quieter site. Use a surveillance-rated drive — see our surveillance hard drives — because desktop drives are not built for 24/7 writing.
4. Decode capability — can it actually show what it records?
A recorder can often record more than it can display. Check the decode spec: an NVR that records sixteen 8MP streams may only decode four of them at full resolution simultaneously. For a monitored site with a spot screen, this matters more than any other line on the datasheet.
Home or small shop: 2–6 cameras
A compact 8-channel with PoE built in covers today's cameras and the headroom rule in one quiet box.
Dahua NVR4108HS-8P — compact 8-channel PoESmall business: 5–12 cameras
Step up to WizSense AI analytics and dual drive bays; take the 16-channel where the plan already says ten cameras.
Dahua NVR4208-8P-EI — 8-channel WizSenseAI analytics and dual drive bays — the small-business default.View product →
Dahua NVR4216-16P-EI — 16-channel, 16 PoESixteen powered ports with headroom for the 10–12 camera plan.View product →
Warehouse or multi-floor: 9–32 cameras
Thirty-two channels, dual drive bays and a separate PoE switch doing the powering.
Dahua NVR4232-EI — 32-channel, dual HDDBrowse the full NVR range and IP cameras, or talk to our team with your camera count and site type — we will spec the recorder and storage for you.