Enter the proposed recording load.
Try a scenario, then compare it with measured bitrates or a manufacturer-specific design estimate. Numbers below use decimal gigabytes (GB) and terabytes (TB).
This estimates recording data, not raw disk capacity or a complete system design.
What the calculator does.
GB per day = cameras × average Mbps × 3,600 × recording hours ÷ 8 ÷ 1,000.
TB for retention = GB per day × retention days ÷ 1,000.
Usable target = TB for retention × (1 + headroom % ÷ 100).
One camera recording at an average of 1 megabit per second for 24 hours produces approximately 10.8 decimal GB of video. Actual rates vary with image detail, movement, light, resolution, compression, frame rate and how the platform records or stores streams. The default numbers are examples, not a Terapixels specification.
Four reasons the real result may differ.
Scene and image settings
Resolution, frame rate, codec, quality targets, analytics and day/night behavior can change bitrate. Sample representative scenes rather than treating every camera as identical.
Recording schedule
Continuous, scheduled and event-triggered recording produce different recorded hours. Pre-event and post-event buffers can add more data than a simple motion percentage suggests.
Audio and metadata
Where enabled, audio, analytics metadata, thumbnails and database or indexing overhead may need additional capacity.
Storage protection
Physical disk requirements depend on RAID or erasure coding, spare disks, failover, archive copies and product-specific behavior. Do not apply a fixed disk multiplier to every platform.
Axis documents target bitrate and retention controls at the camera level. Milestone documents recording and archive settings by camera and storage. Use the current specifications of the proposed platform for final sizing. See source notes.
Turn the estimate into a system scope.
For cloud or hybrid systems, ask which footage remains local, what uploads to the cloud, at what quality, and how bandwidth constraints affect backfill. For on-premises systems, ask how recording servers, storage, archiving and backups are monitored and maintained.
Prove retention in the installed system.
Retention is an operating result, not merely a number entered in the VMS. Review it again after changes to cameras, firmware, codec, frame rate or recording rules.
Questions about video storage.
Can I calculate retention from megapixels alone?
No. Resolution matters, but bitrate also depends on codec, frame rate, scene activity, image quality and recording mode. Use measured or vendor-modeled bitrate for the proposed configuration.
Does motion recording cut storage by a fixed percentage?
No. Activity varies by scene, hours, detection rules and buffer settings. Test representative footage instead of applying a universal motion factor.
Is the calculator result the number of hard drives to buy?
No. It estimates usable recording data plus your chosen headroom. Physical drive count depends on capacity, redundancy, disk performance, recorder software and failover design.
Does cloud video eliminate local storage?
Not necessarily. Some services record at the edge or retain a local copy. Verify where the footage is stored and what happens during a WAN interruption.
Size for evidence, performance and future changes.
Terapixels can assess commercial cameras, VMS choices, storage, network dependencies and retention goals together. A project-specific recommendation should include recording assumptions, a capacity model, failure behavior and a post-installation retention check.
Technical source notes
- Axis Communications, AXIS OS web interface help: bitrate, recording and retention controls.
- Milestone Systems, Storage and archiving: per-device recording and archive behavior.
- Use platform documentation and site measurements for final design. This simple estimator excludes disk configuration, codecs’ rate variability, copies, metadata and specific software overhead.
Plan this with Terapixels.
Share your facility, existing systems and the decision you need to make. We will help identify the right scope and next step.
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