CCTV Storage Calculator

A CCTV storage calculator that sizes the hard drives for a security camera system from real inputs: how many cameras you run, their resolution, the codec (H.264, H.265 or MJPEG), frame rate, scene complexity, how many hours per day you record, and how many days of retention you need. It turns those settings into a total in GB or TB, a per-camera and per-day breakdown, and an optional disk cost estimate so you can budget an NVR or DVR build before buying a single drive. It is aimed at installers scoping a job, IT teams planning a recorder refresh, and homeowners deciding between a 2 TB and an 8 TB disk.

How it works

Surveillance storage is driven almost entirely by bitrate — the amount of data each camera writes per second. Every resolution has a baseline bitrate for a medium-motion scene at 15 fps; this tool then adjusts it for your chosen codec, scene complexity and frame rate. H.265 roughly halves the H.264 figure, while busier scenes (traffic, crowds) compress less and push the bitrate up.

Once the per-camera bitrate is known, the maths is a chain of multiplications:

bytes/s = bitrate (kbit/s) x 1000 / 8, then total = bytes/s x seconds recorded x cameras

The calculator multiplies the per-second figure by the seconds you actually record each day (hours per day x active-recording percentage), then by your retention period and the number of cameras. Sizes are shown in decimal units (1 TB = 1000 GB) to match how drives are sold, and a configurable headroom margin is added on top for RAID parity, the recorder OS, indexing and growth. Frame rate is modelled sub-linearly so lowering fps saves disk without overstating the benefit.

Worked example

Say you are quoting a small retail shop: 8 cameras, all 1080p Full HD, recording with H.265 at 15 fps, continuous 24/7 capture, kept for 30 days.

• Per-camera bitrate works out to about 2 Mbit/s
• That is roughly 21 GB per camera per day, so 170 GB/day across all eight
• Over 30 days the system needs about 5.1 TB of footage

Add 20% headroom and you are looking at around 6.1 TB usable, which in practice means a pair of 4 TB drives or a single 8 TB disk. At a price of 18 per TB the drive cost lands near 110. Switch the cameras to H.264 and the same setup more than doubles to roughly 10 TB of footage — a clear illustration of why codec choice dominates a CCTV storage budget.

Reference: the formula

For one camera over a retention window:

storage_bytes = (bitrate_kbps x 1000 / 8) x (hours_per_day x 3600 x active%) x days

Multiply by the camera count for the system total. Effective bitrate here is base x codec_factor x scene_factor x (0.4 + 0.6 x fps/15), where the codec factors are H.264 = 1, H.265 = 0.5 and MJPEG = 3. These are mid-range industry estimates; a specific camera’s encoder, lighting and bit-rate cap will shift the real number, so treat the result as a well-grounded planning figure rather than a guarantee.

Notes

Everything is calculated locally in your browser — no camera details, prices or results are ever uploaded.