Bitrate is the amount of video data a camera produces every second, measured in bits per second, and it decides how sharp the picture looks, how much disk it fills and how much network it uses. A camera set to 4 megabits per second (Mbps) writes about 43.2 gigabytes a day, so one setting you may never have opened can double or halve your storage bill. This guide answers a simple question, what is bitrate, and shows how to calculate it for a security system, and what it means for the analytics you run on top. For the wider picture of how cameras, recorders and software fit together, start with our overview of what CCTV is and how it works.
Key takeaways
- 1 Mbps equals 1,000,000 bits per second, or about 10.8 GB of video per camera per day.
- Storage in gigabytes = bitrate in Mbps x 10.8 x days of retention.
- 16 cameras at 4 Mbps need about 20.7 TB for 30 days of continuous recording.
- H.265 can deliver similar quality to H.264 at roughly half the bitrate, which can cut that figure to about 10.4 TB.
- Bitrate also sets upload bandwidth: 16 cameras at 4 Mbps send 64 Mbps to a cloud service.
What Is Bitrate in Video Surveillance?
Bitrate is the number of bits a camera sends per second after it compresses the picture. A bit is the smallest unit of digital data, and 8 bits make 1 byte. Because video is a stream of frames, the bitrate is the sum of everything needed to describe those frames: the detail in each one, how many arrive per second and how much changes between them.
Bitrate, resolution and frame rate are different settings
Resolution is the number of pixels in each frame. A 1080p frame holds 1,920 x 1,080 = 2,073,600 pixels, and a 4K frame holds 3,840 x 2,160 = 8,294,400 pixels, about 4 times as many. Frame rate is how many frames arrive per second, commonly 15 to 30 on security cameras. Bitrate is the budget of data you allow for all of it. Raise the resolution without raising the bitrate and the encoder has to throw away detail, so the picture can look soft or blocky even on an expensive camera.
Constant and variable bitrate
With constant bitrate (CBR) the camera sends roughly the same amount of data every second, which makes storage and bandwidth easy to predict. With variable bitrate (VBR) the camera uses less data when the scene is quiet and more when something moves, which saves disk but makes peaks harder to plan for. A busy street at rush hour can use several times the data of the same street at 3 a.m. under VBR. If you size a network for the quiet average, the peaks are where it fails.
What Is Bitrate and How Do You Calculate Storage?
You calculate storage by converting the bitrate to bytes and multiplying by time. One megabit per second is 125,000 bytes per second, which is 10,800 megabytes, or 10.8 GB, per 24 hours. Multiply by the number of cameras and days to size a system.
The bitrates below are examples chosen to show the arithmetic. They are not measurements from any product. Your own cameras will report their configured bitrate in their web interface.
| Example bitrate | Per camera per day | Per camera, 30 days | 16 cameras, 30 days |
|---|---|---|---|
| 1 Mbps | 10.8 GB | 324 GB | 5.2 TB |
| 2 Mbps | 21.6 GB | 648 GB | 10.4 TB |
| 4 Mbps | 43.2 GB | 1,296 GB | 20.7 TB |
| 8 Mbps | 86.4 GB | 2,592 GB | 41.5 TB |
Two adjustments change these numbers. Recording only on motion or events can cut storage sharply: if a scene is active 25 percent of the day, a 4 Mbps camera writes about 10.8 GB instead of 43.2 GB. And a more efficient codec lowers the bitrate itself. Our comparison of H.265 vs H.264 shows how much a codec change can recover.
What Bitrate Do You Need for Security Cameras?
The right bitrate is the lowest one that still lets you do the job you bought the camera for. Identifying a face or reading a plate needs more detail than confirming that a door opened, so the same camera model can be configured differently at different positions.
Match the setting to the task
- General overview of a room or yard: a modest bitrate is often enough, because you only need to see that someone is present.
- Entrances and counters: a higher bitrate protects the detail you need to recognize a person.
- Gates and lanes with moving vehicles: motion makes the encoder work harder, so cheap settings blur plates. See how this plays out in our guide to license plate recognition cameras.
Test before you roll out
Set one camera at three bitrates, record the same scene at night and in daylight, and compare stills. Night footage is where an over-compressed stream shows its weakness first, since low light adds noise that the encoder tries to preserve at the cost of detail elsewhere.
How Does Bitrate Affect Bandwidth and Analytics?
Bitrate is also network load. A recorder on the same switch as the cameras only needs enough local capacity, but video sent off site to a cloud service competes for your upload link. Sixteen cameras at 4 Mbps send 64 Mbps, which is 64 percent of a 100 Mbps uplink before anything else on the network is counted. This is why architecture matters: analytics that run on a local server or on the premises avoid that upload entirely, while cloud analytics trade it for easy scaling and a multi-site view.
It also matters for software that watches the video. An analytics engine can only find what the stream still contains. If compression has smeared a distant figure into a few blocks, no model can recover it. Argu reads feeds from the cameras and recorders you already have at 1080p to 4K and 15 to 30 frames per second over H.264 or H.265, and offers on-premises or private cloud deployment for sites that cannot send footage outside their network. If you are weighing recorders alongside this decision, our guide to DVR vs NVR covers how each handles streams and storage, and our explainer on AI cameras covers where the analytics should run.
Where Argu fits
Argu’s Vision Agents platform connects to existing RTSP or ONVIF streams, IP cameras and NVRs, so you do not need to change camera hardware to add analytics. That makes a sensible bitrate review a low-cost first step: confirm each camera streams at a quality your use case needs, then add detection on top.
Frequently Asked Questions
What is bitrate in simple terms?
Bitrate is how much data a video stream uses every second. A higher bitrate usually means better picture quality and larger files.
Is a higher bitrate always better?
No. Past a certain point extra data adds little visible detail but still fills disks and uses network capacity. Choose the lowest bitrate that keeps the detail your task needs.
How much storage does 1 Mbps use?
About 10.8 GB per camera per day, or 324 GB over 30 days of continuous recording.
What is the difference between bitrate and resolution?
Resolution is the number of pixels in each frame. Bitrate is the amount of data used per second to carry those frames. A high-resolution camera on a low bitrate can look worse than expected.
Does H.265 lower bitrate?
Yes. H.265 can deliver similar quality to H.264 at roughly half the bitrate, which reduces storage and upload needs for the same footage.
Does bitrate affect AI video analytics?
It can. Heavy compression removes the fine detail that detectors rely on, especially for small or distant objects, so analytics work best on streams recorded at a bitrate suited to the scene. See how an RTSP camera shares that stream.
Bitrate is a planning number that touches storage, bandwidth and detection quality at once. If you want to see what your existing cameras can support before you spend on hardware, talk to Argu about the streams you already have.
For a formal definition of the term, see the general reference on bit rate.
Last updated: October 2026
