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How many TB do I need?
Required storage, number of drives and a matching NVR — by camera count, resolution, codec and retention period.
How is it calculated?
For every camera group the bitrate (Mbps) is multiplied by the number of cameras and summed. Mbps is divided by 8 (MB/s), multiplied by recording hours per day (GB/day) and by the retention days. In motion mode the result is multiplied by the activity percentage. Finally the optimal drive configuration is chosen, accounting for formatting loss (≈9%). Example: 8 cameras × 4 Mbps = 32 Mbps = 4 MB/s → ≈ 345.6 GB per day → ≈ 10.4 TB for 30 days → 2 × 6 TB.
Frequently asked questions
What is bitrate and why does it matter?
Bitrate is the amount of data a camera sends per second (Mbps). Storage depends directly on it: a 4 Mbps camera uses about 43 GB per day. The calculator uses typical bitrates, but you can set your own value for every group.
How much do H.265 and H.265+ save?
At the same quality H.265 uses roughly 40–50% less space, and H.265+ (Smart Codec) up to 70% less on static scenes. If your camera and NVR support H.265+, it is the most cost-effective choice.
What does "record on motion only" change?
With motion recording the disk fills only during events. The activity percentage (e.g. 30%) reflects how busy the scene is during the day. For offices, warehouses and night hours it can extend retention 2–3 times.
Why is the usable capacity lower than the label?
Manufacturers count TB in decimal units, operating systems in binary units. That is why a 6 TB drive shows as about 5.46 TB in an NVR. The calculator accounts for this ~9% difference automatically.
Which drive should I use for CCTV?
For 24/7 recording use surveillance-grade drives (WD Purple, Seagate SkyHawk, Hikvision) — they are built for continuous write workload and vibration. Regular desktop drives fail much sooner.