CCTV Storage Calculator | APYS Projects

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CCTV storage from actual recording bitrate

Estimate usable recording capacity for DVR, NVR or camera storage. Use the recording stream’s measured average bitrate or configured planning bitrate, rather than assuming a fixed saving from a camera brand, resolution or codec.

Recording inputs

Cameras using this bitrate

Recording bitrate per camera (Mbps)

Retention (whole days)

Recording duty cycle (%)

Planning margin (%)

The default 4 Mbps is an editable worked example, not a camera specification. Use 100% for continuous recording or when the average bitrate already includes idle periods. If using event-only stream bitrate, enter a measured recording duty cycle; include pre/post-event recording. Do not apply the same activity reduction twice.

Recording capacity estimate

Combined active bitrate—

Recording data—

Including margin—

Whole-TB planning target—

Formula and worked example

Decimal TB = cameras × Mbps per camera × days × 0.0108 × duty-cycle fraction. The factor converts megabits per second to decimal terabytes over 24 hours: 1,000,000 × 86,400 ÷ 8 ÷ 1,000,000,000,000. Capacity with margin = recording TB × (1 + margin/100).

Example: 4 cameras × 4 Mbps × 30 days × 0.0108 × 100% = 5.184 TB. A 20% margin gives 6.2208 TB, rounded upward to a 7 TB usable-capacity planning target. This is not a recommendation for a particular disk size or RAID layout.

Check the complete recording system

Use the saved recording stream, including audio when required; viewing substream settings may differ.
Measure representative day/night scenes and activity. Variable bitrate, noise, frame rate and compression affect actual demand.
For mixed bitrates, calculate each camera group separately and add the unrounded totals.
Compare the target with usable recording capacity after RAID/parity, filesystem reserves, redundancy and other recordings. Manufacturer disk labels alone do not establish usable retention.
Verify recorder throughput, bay count, supported drive capacities, disk health, overwrite settings and actual playback retention after commissioning.

Planning estimate only. A configurable margin does not guarantee retention under every scene condition.

Technical reference: Axis: bitrate control for IP video.

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