Calculate hard disk storage for CCTV cameras, DVR and NVR systems. Estimate recording capacity, HDD size and how long your existing drive can retain footage.
Enter your camera and recording settings. Results update automatically.
Calculated from the settings entered on the left.
Your estimated storage requirement will appear here.
| Number of cameras | — |
| Bitrate per camera | — |
| Recording schedule | — |
| Recording activity factor | — |
| Retention period | — |
| Planning buffer | — |
| Selected recorder | — |
Planning a CCTV surveillance system and wondering how much hard disk space you need? Our CCTV HDD Calculator helps estimate the storage required to record and retain security camera footage for your desired number of days. Enter your camera count, video bitrate, compression codec, recording schedule and retention period to calculate the estimated HDD capacity for your system.
Whether you are installing a few security cameras at home, managing an office surveillance setup or planning a larger IP camera network, this free CCTV hard disk calculator can help you make a more informed storage decision before purchasing a hard drive.
The calculator also lets you estimate recording days on an existing HDD, compare possible hard disk configurations and plan storage with an additional capacity buffer.
A CCTV hard disk calculator is a storage planning tool that estimates how much disk space a video surveillance system will use over time. CCTV cameras continuously or periodically record video, and the size of those recordings depends on several technical settings. The higher the average video bitrate and the longer the recording period, the more storage the system generally needs.
Instead of guessing whether a 1TB, 2TB, 4TB or larger hard drive will be sufficient, use this hard disk calculation for CCTV tool to estimate the required capacity based on your setup.
Estimate the storage needed for multiple cameras and a selected retention period.
Find out approximately how many days of footage an existing hard drive can retain.
Compare drive sizes and the number of drives needed for your estimated storage.
Compare bitrate, codec, recording hours and motion activity assumptions.
Follow these steps to get a useful estimate for your DVR or NVR installation.
Enter the total number of cameras that will record to the system. If you have eight cameras, for example, use eight as the camera count. If cameras use different bitrates, use a suitable average for a rough estimate or calculate separate groups for better accuracy.
Select the camera resolution, such as 1080p, 4MP or 4K, and choose H.264, H.265 or another supported compression setting. Resolution helps provide a starting bitrate estimate, but actual bitrate varies with camera settings and scene activity.
Bitrate is one of the most important inputs in a CCTV storage calculation. It measures how much video data is produced per second. If your camera or recorder displays its average bitrate, use that value. Otherwise, the calculator can use an estimated bitrate as a starting point.
Select the number of hours the cameras record each day. Continuous recording normally means 24 hours per day. A schedule limited to certain hours will generally use less storage than recording continuously at the same bitrate.
Enter how many days of footage you want to keep. A 30-day retention period requires more storage than a 7-day period when all other settings remain unchanged.
Check the estimated raw storage, buffered capacity, daily storage usage and suggested drive configuration. Before buying a drive, confirm that your DVR or NVR supports the selected capacity and the number of installed drives.
The core storage estimate can be calculated using the total average video bitrate and the time spent recording. This method is more useful than relying on camera resolution alone.
For multiple cameras, calculate the storage for one camera and multiply it by the number of cameras, assuming they use the same average bitrate and recording schedule.
Hard drive manufacturers generally express capacity using decimal units: 1TB equals 1,000GB. The capacity available to store recordings can differ from the nominal drive capacity because of system formatting, recorder requirements and reserved space.
Suppose you have four cameras, each recording at an average bitrate of 2Mbps for 24 hours per day. You want to retain footage for 30 days.
| Setting | Example value |
|---|---|
| Number of cameras | 4 |
| Average bitrate per camera | 2 Mbps |
| Recording schedule | 24 hours per day |
| Retention period | 30 days |
| Approximate storage per camera per day | 21.6 GB |
| Approximate total daily storage | 86.4 GB |
| Approximate raw storage for 30 days | 2.592 TB |
With a 10% planning buffer, the estimate becomes approximately 2.85TB before accounting for any unusable capacity allowance. A supported 4TB drive may be a reasonable starting point for this example, but actual requirements depend on real bitrate, recorder settings and how much capacity is available for recordings.
Higher-resolution video can contain more data and may need more storage, especially when configured for higher detail. However, resolution alone does not determine storage. Compression efficiency, scene complexity and bitrate settings also matter.
H.264 and H.265 are video compression standards. H.265 may achieve comparable image quality at a lower bitrate in suitable conditions, which can reduce storage needs. The actual saving varies by camera, encoder settings and scene. Manufacturer-specific formats such as H.265+ may behave differently.
Higher frame rates can increase data usage, depending on the encoding configuration. Lower frame rates may reduce storage but can affect how smoothly fast-moving events appear in recorded footage.
Continuous recording stores video throughout the selected recording schedule. Motion-based recording stores video based on configured detection rules and activity. Its storage savings depend on the scene, detection settings, pre-recording and post-recording periods, and whether the system records at a low bitrate when idle.
Audio recording and additional video streams may add to the overall storage requirement. Check whether the bitrate entered into the calculator represents the main stream only or includes all recorded data streams.
The number of days you need to preserve recordings directly affects capacity. Businesses and sites with specific security or regulatory requirements should confirm their retention policies before finalizing a drive size.
A DVR commonly records video from compatible analog or HD-over-coax cameras. When planning a DVR hard disk, check its supported camera formats, recording resolution, total channel count, maximum supported HDD capacity and number of drive bays. Use the actual configured bitrate for the best estimate.
An NVR records video from supported IP cameras over a network. Its storage needs depend on the combined recording bitrates of the cameras, recording schedules and retention requirements. Also check the recorder's maximum supported drive capacity and whether the specified capacity applies per drive or across the whole system.
For IP cameras, camera resolution and FPS can provide a starting estimate, but the configured encoding bitrate is usually a better input. If your cameras have different resolutions or settings, calculate them in separate groups and add the resulting storage estimates together.
A surveillance HDD calculator helps estimate the storage required for a security camera installation before you purchase drives. For a larger installation, calculate each camera group separately, add the total recording demand, and check compatibility with the recording equipment.
The number of recording days that fit on a drive depends on the total daily video data. The table below shows an illustrative example using a total combined bitrate of 4Mbps for all cameras, continuous 24-hour recording and decimal HDD capacity. It excludes reserved space and other recording overhead.
| Nominal HDD | Approx. raw storage time | Important note |
|---|---|---|
| 500GB | About 11.6 days | Actual usable time may be lower |
| 1TB | About 23.1 days | Depends on actual bitrate |
| 2TB | About 46.3 days | Before capacity allowance |
| 4TB | About 92.6 days | Before capacity allowance |
| 8TB | About 185.2 days | Before capacity allowance |
These figures are examples for a combined bitrate of 4Mbps, not universal retention figures for a particular camera count or resolution. If the combined bitrate doubles, the estimated recording duration is roughly halved under the same conditions.
Find the average bitrate per camera, calculate the data generated during the daily recording schedule, multiply by the number of cameras and retention days, and add a planning buffer. Check the usable capacity and supported drive sizes for your recorder.
A useful CCTV HDD calculator lets you enter actual bitrate, camera count, recording hours, codec and retention days. A tool that also estimates recording days for an existing drive can help you compare storage options.
There is no single storage requirement for every camera. A camera recording at 2Mbps for 24 hours generates approximately 21.6GB per day using decimal units, before additional overhead. Higher bitrates use more storage.
It may be sufficient for a small setup with low total bitrate or a short retention period. Whether it is enough depends on the number of cameras, recording settings and required number of days. Enter those values in the calculator to estimate the result.
It depends on the combined bitrate and retention period. For four cameras recording continuously at 2Mbps each, the raw estimate is approximately 2.592TB for 30 days. A 2TB drive would not provide that full retention period under these assumptions.
H.265 can reduce storage needs compared with H.264 at comparable image quality in suitable conditions. The exact reduction depends on the encoder, image content and configuration. Use the actual bitrate rather than assuming a fixed percentage saving.
Divide the usable drive capacity by the total daily storage requirement. Our calculator includes an existing HDD mode for estimating recording duration from the selected capacity and camera settings.
The basic bitrate-to-storage formula is the same. The main differences are camera compatibility, supported codecs, recorder limits and the number and capacity of supported drives.
It can reduce storage if the system records only during detected events. The actual saving depends on how active the scene is, the configured detection rules and whether the system records continuously at a lower bitrate between events.
Possible causes include a higher actual bitrate, more active scenes, audio recording, longer recording hours, additional streams or a retention configuration that differs from your estimate. Check the recorder's recording and bitrate settings to investigate.
Yes. You can use the calculator for compatible IP camera systems by entering the combined camera count, average bitrate, recording schedule and retention period. For cameras with different settings, calculate each group separately.
Yes. The calculator is designed to provide storage estimates in your browser without requiring a paid calculation service.
Use the CCTV HDD Calculator above to estimate storage for your surveillance setup, compare supported HDD sizes and plan a suitable recording retention period. For the most reliable estimate, enter the actual average bitrate from your camera or recorder and confirm the hardware specifications before purchasing drives.