Calculator
CCTV storage and retention
Camera count × recorded bitrate × recording hours, in decimal TB, with the free-space reserve and any RAID overhead kept as separate steps.
Everything runs in your browser. Nothing is sent anywhere, and no figure is saved or put into a link.
Your recording
Read it from your recorder's stream settings. Do not apply a codec saving on top of a measured figure.
Disks are not filled to 100%. 80% is a common working reserve.
1 = no RAID. Mirroring is roughly 2×. Kept separate from the reserve above, never folded into it.
What to buy
Decimal units: 1 TB = 1000 GB, the way drives are sold. Your operating system will report less. Formula version 1.0.0.
Retention is your recorder’s job, not the analytics layer’s: PGAK reads the streams and does not change how long footage is kept.
How it is calculated
Bytes = cameras × bitrate(Mbps) × 1,000,000 × hours × 3600 × days ÷ 8. TB = bytes ÷ 1e12 (decimal). Nominal = recorded ÷ usable fraction.
Worked example
16 cameras, 2 Mbps each, recording 24 hours a day for 30 days.
10.368 TB of footage. At 80% usable capacity that is 12.96 TB to buy, before any RAID overhead.
Formula version 1.0.0. Reviewed 23 September 2026.
What this does not tell you
Uses the bitrate you measured or were quoted. No codec saving is applied on top of an already-measured bitrate, and RAID is never folded into the reserve.
Published because buyers need the number. It is not a claim that PGAK sells a product for it.
Want this checked against your own site?
A PGAK business-case assessment goes through your cameras, your quotation and the numbers you entered here, and says plainly where the case is weak. Have your retention checked.
The result above is yours to keep either way — print it, save it, no contact details required.
Get your free camera audit.
Tell us your WhatsApp number and how many cameras you have. We call within one working hour, 9 am to 7 pm, Monday to Saturday. Your audit report follows within 48 hours — on the cameras you already own.