How it works
Start with an observed average bitrate from your recorder or camera rather than inferring it from resolution alone. Multiply the cameras by their average bitrate, convert bits to bytes, and multiply by the number of seconds recorded. This model assumes all entered cameras share that bitrate and schedule. For different camera groups, run each group separately and add the capacity estimates. The editable extra-capacity percentage adds space above the calculated data volume; 20% is a planning assumption, not a retention guarantee.
The formulaRecorded bytes = cameras × Mbps × 1,000,000 ÷ 8 × hours/day × 3,600 × days
Target usable capacity = recorded bytes × (1 + extra % ÷ 100)
1 TB = 10¹² bytes; 1 TiB = 2⁴⁰ bytes
Put it into practice
EXAMPLEFour cameras at 4 Mbps, continuously recording for 30 days, produce about 5.184 TB of data. Adding 20% gives a target of 6.2208 TB of usable capacity, displayed as approximately 6.221 TB. This is not a recommendation to buy a drive of that nominal size.
EXAMPLEEight cameras at 2 Mbps, recording an average of 6 hours per day for 14 days, produce 0.6048 TB. With no extra allowance, that is the target usable capacity. The six-hour estimate must include any pre-event and post-event recording.
Good to know
Does changing resolution or codec automatically change this result?
No. Resolution, frame rate, compression, scene detail and motion affect bitrate, but there is no universal conversion. Enter the resulting measured or configured bitrate yourself. An average may underestimate busy periods; a configured maximum gives a different, more conservative scenario.
How should I estimate motion recording?
Use realistic recorded hours per day from a comparable installation, including event buffers. Motion activity can change substantially, so check a continuous-recording scenario as well. A zero-hour entry represents no recording and produces zero storage.
Is this raw disk capacity or usable recorder capacity?
The result is a target for usable recording capacity. RAID redundancy, formatting, the recorder operating system, reserved space and other data reduce the amount available from nominal disks. This tool does not choose a RAID layout or calculate drive failure tolerance.
Does the bitrate also tell me the network bandwidth needed?
The combined rate is the sum of the entered streams while recording. It excludes protocol overhead, extra live-view streams and traffic peaks. Do not treat it as a switch-throughput or uplink guarantee.