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There is no fixed storage amount for a 2K or 4K security camera: the main inputs are its configured bitrate and how many hours it records. As a planning example, a CCTV calculator using H.265 at 4 Mbps for a 4MP/2K camera estimates about 43.2 GB per day; at 8 Mbps for an 8MP/4K camera, about 86.4 GB per day. Those are assumed bitrates, not universal camera specifications.
Estimate storage with bitrate and recording time
For approximate decimal gigabytes, use:
GB = bitrate in Mbps × 0.45 × recording hours per day × retention days × number of cameras
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The 0.45 factor converts each Mbps of video into about 0.45 GB per hour. This formula makes clear why resolution alone cannot tell you how large a drive you need: you also need the stream bitrate, recording schedule, retention period, and number of cameras. The Pentagon Solutions CCTV Storage Calculator uses this arithmetic for its estimates.
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Continuous-recording examples
| Example setup | Per camera per day | Per camera for 30 days |
|---|---|---|
| 4MP/2K, H.265, 4 Mbps | 43.2 GB | About 1.30 TB |
| 8MP/4K, H.265, 8 Mbps | 86.4 GB | About 2.59 TB |
These figures are calculator examples based on the stated bitrate assumptions and 24 hours of continuous recording, using decimal units. For a multi-camera example, the same calculator estimates 11.4 TB for eight 4MP cameras recording continuously at H.265 and 4 Mbps for 30 days; it uses a nominal 12 TB drive as an example. Formatted capacity and recorder settings affect how much footage a drive actually holds.
#1 Best Overall
- Engineered for mainstream surveillance systems
- WD AllFrame technology delivers optimizations for write-intensive, low bit-rate, high stream-count workloads typical to mainstream surveillance applications
- Supports up to 180 TB/yr workload rate(3) | (3) Workload Rate is defined as the amount of user data transferred to or from the hard drive. Workload Rate is annualized (TB transferred ✕ (8760 / recorded power-on hours)). Workload Rate will vary depending on your hardware and software components and configurations.
- Support for up to 16 bays(7) | (7) 1TB through 2TB support up to eight bays; 3TB and above support up to 16 bays.
- Tarnish-resistant components(6) | (6) Tarnish resistant components for capacities 3TB and higher.
Why 2K or 4K does not determine storage by itself
Resolution describes the image dimensions, not the amount of video data recorded over time. A higher resolution can require more data, but the actual stream bitrate also depends on frame rate, image quality, compression, scene activity, and camera configuration. Western Digital’s surveillance capacity calculator lets users account for factors such as camera count, resolution, FPS, compression, picture quality, scene activity, and retention.
Codec and camera settings
H.264 and H.265 compress video differently, but the storage saving from switching codecs is not a guaranteed fixed percentage. It varies with the camera, recorder, settings, and footage. SanDisk describes H.265/HEVC as a newer compression format and advises confirming that the DVR or NVR supports the selected format. Check the camera’s actual bitrate settings rather than estimating from the codec name alone. See the SanDisk surveillance microSD storage calculator and its surveillance storage capacity calculator for additional estimating inputs and assumptions.
Rank #2
- Built for video DVR and NVR security camera systems, SkyHawk delivers video-optimized storage
- Support workloads of up to 180TB/year—that's 64 simultaneously streaming HD cameras with zero dropped frames
- Built-in RV sensors allow drives to maintain performance in multi-bay systems, offering the flexibility to scale systems when more storage is needed
- Lower power consumption reduces heat emissions and improves reliability—plus, drives can easily be monitored with SkyHawk Health Management
- Enjoy long-term peace of mind with 1M hours MTBF, an included three-year limited warranty, and three-year in-house Rescue Data Recovery Services
Continuous versus motion-triggered recording
Continuous recording is easier to size because the recording hours are known. Motion-triggered recording may use less storage, but the reduction depends on how often activity triggers recording. A busy driveway or shop can generate much more footage than a quiet room, so do not assume a standard motion-recording discount. Seagate’s video storage calculator for surveillance includes daily recording hours and motion recording as inputs.
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- Find each camera’s bitrate. Use the configured maximum bitrate for a conservative estimate. An observed average bitrate can provide a closer estimate for a particular scene and schedule.
- Record the video settings. Note codec, resolution, FPS, and whether recording is continuous, scheduled, or motion-triggered.
- Set the retention target. Choose how many days of footage to keep and count all cameras sharing the storage pool.
- Calculate each group separately. Apply the formula to cameras with the same settings, then add the results for groups with different bitrates or schedules. A manufacturer calculator can also help if you enter the actual settings.
- Check recorder compatibility. Before choosing a drive, confirm the NVR or DVR’s supported drive capacity and number of bays. Allow for formatted capacity and practical headroom.
Calculator results are estimates, not guaranteed retention periods. SanDisk notes that estimates can vary with format, compression ratio, resolution, FPS, color depth, system capabilities, hardware, configurations, settings, and software. Its estimator assumes 30-bit color depth for 4K and higher resolutions and 16-bit color depth for lower resolutions.
Rank #3
- Built faster for video DVR and NVR security camera systems, SkyHawk delivers video-optimized storage
- Support workloads of up to 180TB/year—that's 64 simultaneously streaming HD cameras with little to zero dropped frames
- Quieter—with built-in RV sensors to allow drives to maintain performance in multi-bay systems, offering the flexibility to scale systems when more storage is needed
- Efficient power consumption reduces heat emissions and improves reliability—plus, drives can easily be monitored with SkyHawk Health Management
- Enjoy long-term peace of mind with 1M hours MTBF, an included three-year limited warranty, and three-year in-house Rescue Data Recovery Services
Choose storage that fits the recorder and workload
The storage capacity you need follows from your retention target and recording settings; the recorder determines which drives you can install. Verify its capacity limits and available bays before buying. Western Digital describes its Purple and Purple Pro drive families as designed for surveillance workloads and continuous recording environments, but the appropriate capacity still depends on your system and target retention.
If a camera records to a microSD card instead of, or alongside, an NVR, check the camera’s supported card capacity and recording format. Local-card estimates are not interchangeable with a shared recorder’s storage calculation.
Quick Recap
Best Value
- 1TB Capacity, Intellipower (5400RPM~7200RPM) Rotation Speed, 64MB Cache
- 3.5" Internal Hard Drive, SATA III 6.0Gb/s, Bulk Single Pack, No Cable or Accessories included.
- Designed for 24/7 Operation, Lower Power consumption & Heavy Duty, Cool Temperature
- For Surveillance Hard Drive, Network Storage (NAS), set-top boxes (PVR, DVR, NVR and IPTV), media servers and media centers.
Rank #4
- Engineered for mainstream surveillance systems.
- WD AllFrame technology delivers optimizations for write-intensive, low bit-rate, high stream-count workloads typical to mainstream surveillance applications
- Supports up to 180 TB/yr workload rate
- Capacity up to 8TB
- Support for up to 16 bays
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