CCTV

VMS / NVR Server

Enter the number of cameras, bitrate and retention and I compute the recording bandwidth, storage (TB), write IOPS, server RAM and how many servers you need by their throughput/channel limit.

redzilla.cl — vms

Bandwidth

0 Mbps

recording all cameras

Storage

0 TB

for the chosen retention

Write IOPS

sequential write (low)

Server RAM

0 GB

base + per camera

Servers

by throughput/channel limit

Cameras / server

even split

Why that many servers?

Criterion	Calculation	Servers

Storage uses decimal TB (1 TB = 10¹² bytes): BW(Mbps)/8 = MB/s, × 86400 s/day × days ÷ 10⁶. Add headroom for the operating system, indexes, RAID and growth. IOPS are low because recording is large-file sequential writing (≈ one stream per camera).

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How it works

The calculator sizes the recording server of a CCTV system from the number of cameras, the bitrate per camera and the retention days. Recording bandwidth is Mbps = cameras × bitrate and storage is computed in decimal TB (1 TB = 10¹² bytes): TB = (Mbps/8) × 86400 × days ÷ 10⁶. Write IOPS are estimated as one sequential stream per camera, because recording video is sequential writing of large files, not random I/O.

It also splits the load across servers according to two configurable limits (advanced section): maximum throughput per server (300 Mbps by default, typical for a VMS on standard hardware) and maximum channels per license or software (128 by default). The server count is max(⌈total Mbps / Mbps limit⌉, ⌈cameras / channel limit⌉), and RAM is estimated as base + cameras × RAM per camera (8 GB + 0.25 GB per channel by default).

Example: 64 cameras at 4 Mbps with 30 days of retention

Bandwidth: 64 × 4 = 256 Mbps of sustained recording.
Storage: 256/8 = 32 MB/s × 86400 × 30 ÷ 10⁶ ≈ 82.9 TB.
Servers: by throughput ⌈256/300⌉ = 1 and by channels ⌈64/128⌉ = 1 → 1 server is enough.
Estimated RAM: 8 + 64 × 0.25 = 24 GB, with about 64 sequential write IOPS.

Frequently asked questions

How many cameras can a VMS server handle?

It depends on two caps: recording throughput (a standard server handles on the order of 300–600 Mbps depending on disks and network) and the channel limit of the software or license (typically 64 to 128). Whichever cap is reached first rules: with high-bitrate 4K cameras, throughput limits long before channels do.

Why are NVR IOPS so low?

Because video recording is sequential writing of large blocks: each camera keeps roughly one continuous stream, so 64 cameras mean about 64 sustained write operations. That is why surveillance drives prioritize sustained throughput over random IOPS; random I/O only appears with simultaneous playback and analytics.

What is the difference between an NVR and a VMS server?

An NVR is a dedicated appliance with closed software and a fixed channel capacity, aimed at small and medium installations. A VMS (Video Management System) is software running on standard servers that scales horizontally: you add recording servers as cameras grow. The math in this tool applies to both.

Does the calculated storage include RAID and the operating system?

No: it is the net video volume. You must add the operating system space, the VMS databases and indexes, the RAID redundancy loss (for example, one full disk in RAID 5) and growth margin. A practical rule is to provision an extra 20–30 % on top of the result.

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Disclaimer

We take great care to keep every tool accurate and review it thoroughly; even so, we can't guarantee it is free of errors or take responsibility for how the results are used. We recommend double-checking anything critical.

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