CCTV bandwidth and storage calculator
Enter your cameras, resolution, codec, frame rate, scene activity, recording mode and retention days to estimate bitrate per camera, total network bandwidth and recorder storage. As a guide, 16 cameras at 4MP on H.265 at 15 fps, recording continuously for 30 days, need about 9.72 TB. Results are estimates from the documented assumptions below.
Last updated 27 October 2026Change any input below
Estimate your CCTV bandwidth and storage
Change any input and the results update straight away. Everything runs in your browser.
Estimate for 16 cameras, 4MP, H.265, 15 fps, medium activity, continuous, 30 days
- Bitrate per camera
- 1.88 Mbps
- Total bandwidth
- 30.0 Mbps
- Storage per day
- 324 GB
- Storage for the retention period
- 9.72 TB
- Planning size with 20% headroom
- 11.66 TB
Estimates only, using the assumptions in the table below. Real bitrates depend on the camera, its settings and the scene.
JavaScript is off, so the figures shown are the worked example. Use the assumptions table to work out your own.
What assumptions does the calculator use?
Bitrate per camera = resolution figure × codec factor × frame-rate factor × activity factor. Storage multiplies that by the cameras, the share of the day recorded and the retention days.
The resolution figures are typical starting points in line with common camera default settings, not measurements from any one make or model. Your own cameras will differ, so check a real bitrate on your recorder before you buy drives.
| Input | Value | Basis |
|---|---|---|
| Resolution: 720p (1MP) | 2 Mbps | H.264 main stream at 30 fps with a medium scene |
| Resolution: 1080p (2MP) | 4 Mbps | H.264 main stream at 30 fps with a medium scene |
| Resolution: 4MP | 6 Mbps | H.264 main stream at 30 fps with a medium scene |
| Resolution: 5MP | 8 Mbps | H.264 main stream at 30 fps with a medium scene |
| Resolution: 4K (8MP) | 12 Mbps | H.264 main stream at 30 fps with a medium scene |
| Codec: H.264 | × 1 | Reference codec |
| Codec: H.264+ (smart codec) | × 0.7 | Smart codecs save most in quiet scenes, less in busy ones |
| Codec: H.265 | × 0.5 | Commonly quoted as about half the bitrate of H.264 for similar quality |
| Frame rate | × (0.25 + 0.75 × fps ÷ 30) | Key frames and fixed overhead do not shrink with fps, so halving fps does not halve the bitrate |
| Scene activity: Low | × 0.6 | Quiet indoor or empty yard at night |
| Scene activity: Medium | × 1 | Typical yard, car park or warehouse aisle |
| Scene activity: High | × 1.5 | Busy road, trees in wind, rain or infrared noise at night |
| Recording mode | × share of day recorded | Continuous is 100%; motion-only uses the percentage you enter. Network bandwidth is unchanged |
| Units | GB = Mbps × 86,400 ÷ 8 ÷ 1,000 | Decimal gigabytes and terabytes, as drive makers use. Formatted drives show slightly less |
How much storage does a CCTV camera use?
One camera streaming at 2 Mbps all day writes about 21.6 GB, or about 648 GB over 30 days. Multiply by your cameras and retention days and the total climbs quickly, which is why codec and frame rate matter so much.
The sum is simple: megabits per second × 86,400 seconds in a day ÷ 8 bits per byte gives megabytes, then divide by 1,000 for gigabytes. Motion-only recording cuts that by the share of the day that is not recorded. Drive capacity is sold in decimal terabytes, and a recorder also needs some space for its own system, so plan for headroom rather than filling the disks exactly.
How much bandwidth does a CCTV camera need?
Each camera needs its own bitrate on the local network, and the recorder must take the total. The worked example above, 16 cameras at 1.88 Mbps each, adds up to about 30.0 Mbps into the recorder.
That traffic stays on the site's network, usually through a PoE switch. Check that the switch uplink and the recorder's incoming bandwidth limit are comfortably above the total, and remember that cameras normally stream all the time, even when the recorder is only saving motion.
H.264 vs H.265: how much does the codec save?
H.265 is commonly quoted as needing about half the bitrate of H.264 for similar picture quality, so the calculator applies a factor of 0.5. Smart codecs such as H.264+ save a lot in quiet scenes but less in busy ones, so they get 0.7.
The saving is the same in storage and bandwidth, which makes the codec one of the biggest levers on most systems. Check first that the recorder, the viewing app and anything else that reads the streams can decode H.265.
How do frame rate and resolution change the result?
Resolution sets the starting bitrate, and frame rate scales it. More pixels and more frames both add bits, but not in a straight line.
Doubling the frame rate does not double the bitrate, because key frames and other overhead are sent either way; the model keeps a quarter of the bitrate fixed and scales the rest with frame rate. For general overview cameras, 10 to 15 fps is a common setting. Busy scenes, rain and night-time infrared noise raise bitrate too, which is what the activity setting covers.
How should you read the results?
Treat them as a planning estimate. Size the recorder from the headroom figure, then check real bitrates once the cameras are running.
- Enter the number of camerasCount every camera that records, including any you plan to add soon.
- Choose resolution and codecPick the main-stream resolution and the codec set on the cameras or recorder.
- Set the frame rate and scene activityUse the recording frame rate, and pick the activity level that best matches a typical camera view.
- Choose the recording modeContinuous, or motion-only with the share of the day you expect motion.
- Enter the retention period and read the resultsRead bitrate, total bandwidth and storage, then size the recorder from the headroom figure.
What about remote viewing and cloud upload?
Only what leaves the site uses the internet connection. Watching live on a phone usually pulls a small sub-stream per camera, while cloud recording sends full streams off site all the time.
For remote viewing, allow for the number of cameras people watch at the same time rather than every camera. For cloud recording, the upload needs to cover the total bandwidth figure with room to spare, and an on-site recorder keeps recording if the internet drops. Many business connections have far less upload than download, so check the upload speed first.
Planning to add AI detection to existing cameras? Read how Woodcock AI works, the guide on how to choose an AI CCTV system, and our RTSP set-up guide for Hikvision. Installers can see the installer and reseller programme.
Embed this calculator
Installers, consultants and IT teams are welcome to use the calculator on their own sites. Paste this code where you want it to appear.
<iframe src="https://www.woodcock.ai/tools/cctv-bandwidth-storage-calculator/embed/" title="CCTV bandwidth and storage calculator" width="100%" height="900" style="border:0;max-width:760px" loading="lazy"></iframe>
<p><a href="https://www.woodcock.ai/tools/cctv-bandwidth-storage-calculator/">CCTV calculator by Woodcock AI</a></p>CCTV bandwidth and storage: common questions
How much storage do 16 cameras need for 30 days?
With 4MP cameras on H.265 at 15 fps, a medium scene and continuous recording, this calculator estimates about 9.72 TB, or about 11.66 TB with 20% headroom. Higher resolution, frame rate or activity pushes it up; motion-only recording brings it down.
How long should CCTV footage be kept in the UK?
UK data protection law does not set a fixed period. The ICO's guidance is to keep footage no longer than you need it for the reason you record. Around 30 days is a common choice; set a period you can justify and size the storage for it.
Does motion-only recording reduce network bandwidth?
Usually not. The cameras keep streaming to the recorder all the time so it can catch the start of an event; motion-only recording mainly saves disk space.
Will every recorder play H.265?
No. Many recent recorders and viewing apps support it, but some older recorders and software only decode H.264. Check the recorder, the viewing software and any other system that reads the streams before switching.
Why is my real bitrate different from the estimate?
Bitrate depends on the camera, its bitrate cap and constant or variable bitrate setting, the key-frame interval, lighting and the scene. Night-time infrared noise, rain and moving trees can raise it sharply. Check the live bitrate on the recorder and adjust.
How much upload do I need to view cameras remotely?
Each live view usually pulls the camera's sub-stream, which is far smaller than the main stream. Allow for the number of cameras viewed at the same time. Cloud recording is different: it sends full streams off site all the time.
Is the calculator free to use?
Yes. It runs in your browser with no sign-up, and nothing you enter is sent anywhere.
Can I put this calculator on my own website?
Yes. Copy the embed code on this page. Please keep the credit link to Woodcock AI.
Planning cameras for a new or existing site?
A site assessment checks your cameras, recorder and network, and shows what AI detection could watch for on your site.