A DVR storage calculator tells you how much hard drive space you need to record video for a given number of days. The answer depends on camera count, resolution, frame rate, codec, and how much motion the cameras see. This 2026 guide gives you ready-to-use numbers for common home and small-business setups, explains the math behind them, and points out the traps that eat through storage faster than expected.
DVR Storage Calculator: Quick DVR Storage Reference Table
These numbers assume 24/7 continuous recording at 15 fps with H.265 encoding. They are the realistic ceiling for most DVR/NVR systems in 2026. Using a DVR storage calculator removes the guesswork from planning your system.
| Cameras | Resolution | 1 Day | 7 Days | 14 Days | 30 Days |
|---|---|---|---|---|---|
| 4 | 1080p | 50 GB | 350 GB | 700 GB | 1.5 TB |
| 4 | 4K | 180 GB | 1.25 TB | 2.5 TB | 5.4 TB |
| 8 | 1080p | 100 GB | 700 GB | 1.4 TB | 3 TB |
| 8 | 4K | 360 GB | 2.5 TB | 5 TB | 10.8 TB |
| 16 | 1080p | 200 GB | 1.4 TB | 2.8 TB | 6 TB |
| 16 | 4K | 720 GB | 5 TB | 10 TB | 21.6 TB |
| 32 | 1080p | 400 GB | 2.8 TB | 5.6 TB | 12 TB |
Round up by 20 percent when sizing a new drive. Real-world bitrates spike during motion and scene changes.
The DVR Storage Formula
The storage math is straightforward:
Storage (GB) = (Bitrate kbps / 8) x Duration (s) / 1,000,000 x Cameras A DVR storage calculator is the easiest way to estimate your exact requirements.
To size for retention days:
Total storage (GB) = (Bitrate kbps / 8) x 86,400 / 1,000,000 x Cameras x Retention days A DVR storage calculator is the easiest way to estimate your exact requirements.
Typical bitrates for surveillance video at 15 fps:
- 720p H.265: 1 Mbps
- 1080p H.265: 2 Mbps
- 4K H.265: 8 Mbps
- 720p H.264: 2 Mbps
- 1080p H.264: 4 Mbps
- 4K H.264: 16 Mbps
H.265 roughly halves storage vs H.264 for the same visual quality. Always enable H.265 if your cameras and recorder support it. A DVR storage calculator is the easiest way to estimate your exact requirements.
Worked Example
Setup: 8 cameras at 4K, 15 fps, H.265, 24/7 recording, 14-day retention.
- Bitrate per camera: 8,000 kbps.
- Per second per camera: 8,000 / 8 = 1,000 KB/s.
- Per day per camera: 1,000 KB x 86,400 s = 86,400,000 KB = 86.4 GB.
- Per day 8 cameras: 691 GB.
- 14 days 8 cameras: 9,670 GB = 9.7 TB.
Buy a 10 TB drive and leave room for spikes. 12 TB is safer if you enable event replay or dual-stream recording. Run the numbers through a DVR storage calculator to get precise sizing.
Factors That Change Storage Needs
1. Frame Rate
15 fps is the surveillance default. Dropping to 10 fps saves 25 to 33 percent storage. Jumping to 30 fps roughly doubles storage. For license plate capture at busy driveways, 30 fps is worth it; for hallway coverage, 10 fps is fine. A DVR storage calculator is the easiest way to estimate your exact requirements.
2. Motion-Triggered Recording
Record only on motion and storage needs drop 50 to 80 percent for most homes. Downside: missed pre-event frames. Modern NVRs mitigate this with a 5-to-10-second motion buffer so you never lose the run-up to an event. A DVR storage calculator is the easiest way to estimate your exact requirements.
3. Codec
H.265 is about 50 percent more efficient than H.264. H.265+ (Hikvision) or H.265 Smart Codec (Dahua) adds scene-aware compression for another 30 percent savings. Always check that playback devices can decode the codec you pick.
4. Dual Streams
Many IP cameras record a main stream (high res) and a sub-stream (low res) for mobile viewing. Some DVRs save both, doubling storage. Configure the recorder to store only the main stream. A DVR storage calculator is the easiest way to estimate your exact requirements.
5. Overlay and Audio
Audio adds about 128 kbps per channel (negligible). Time/date overlay adds zero. Both safe to leave on.
Storage Tips for 4K and Higher
- Use H.265 or H.265+. Not optional at 4K.
- Drop frame rate to 15 fps unless you truly need 30.
- Consider motion-triggered recording for sides/back of house, full-time for entrances.
- Use event-based retention (keep motion clips forever, delete idle clips after 7 days).
- Buy surveillance-grade drives (WD Purple, Seagate SkyHawk). Consumer drives fail under 24/7 write loads.
TV DVR Storage (OTA)
For Tablo, TiVo, and Fire TV Recast, the numbers are different. OTA broadcasts at ATSC 1.0 run roughly 10 Mbps at 1080i.
| Drive | HD hours (ATSC 1.0) |
|---|---|
| 500 GB | ~75 hours |
| 1 TB | ~150 hours |
| 2 TB | ~300 hours |
| 4 TB | ~600 hours |
| 8 TB | ~1,200 hours |
If you record 2 hours of TV a day, a 1 TB drive lasts about 75 days before you start overwriting. Most families find 2 TB to be the sweet spot. Run the numbers through a DVR storage calculator to get precise sizing.
RAID vs Single Drive
Home DVR: single drive is fine. If it fails you lose recordings, but the cost of RAID does not justify it for residential footage. Using a DVR storage calculator removes the guesswork from planning your system.
Business DVR: RAID 1 (mirror) or RAID 5 (striped with parity) is smart. Losing 30 days of surveillance because a drive died is a real risk. Use a NAS-style NVR (Synology Surveillance Station, QNAP, Unraid) or an NVR that supports hot-swap bays. Using a DVR storage calculator removes the guesswork from planning your system.
External vs Internal Drives
Most DVRs and NVRs have 1 to 4 internal SATA bays. Some also support USB 3.0 external drives. Internal drives are preferred for 24/7 reliability. External USB drives are fine for expansion but can disconnect unexpectedly. Using a DVR storage calculator removes the guesswork from planning your system.
Common Storage Traps
- Consumer drives in surveillance use. WD Blue and Seagate Barracuda are not rated for 24/7 write loads. They fail in 6 to 18 months.
- Underestimating motion spikes. A 2 Mbps 1080p cam can spike to 6 Mbps in high motion. Always leave 20 percent headroom.
- Forgetting H.264 is still the default on many kits. Switch to H.265 in camera settings to halve storage.
- Over-retention. Keeping 30 days when you actually only ever review the last 7. Shorten retention to extend useful life of the drive.
Frequently Asked Questions
How much storage do I need for 4 cameras?
4 cameras at 1080p H.265 need about 1.5 TB for 30 days of 24/7 recording. At 4K H.265, plan on 5 to 6 TB for the same window.
How much storage for 8 cameras at 4K for 30 days?
Plan on 10 to 12 TB with H.265 at 15 fps. If you need 30 fps, double that.
Does motion-triggered recording save space?
Yes. 50 to 80 percent in typical home settings. Just make sure your NVR has a 5-to-10-second pre-motion buffer so you do not miss the approach to an event.
Can I use a WD Purple in a regular PC?
Yes but it is tuned for sequential writes, not random reads. It is fine in a PC; it is not ideal as a boot drive.
Is 10 TB enough for an 8-camera 4K NVR?
For 14 days with H.265, yes. For 30 days, upgrade to 12 to 16 TB. For motion-only recording, 10 TB will last 30+ days easily.
Bottom Line
The easiest way to size DVR storage is to look up your camera count and resolution in the table at the top, then multiply for the retention days you need. For 4K cameras, use H.265, 15 fps, and motion-triggered recording to cut storage by up to 80 percent. Use surveillance-grade drives and leave 20 percent headroom. For OTA TV DVRs, 2 TB covers 300 hours which is plenty for most households.
For related buying guides, read our Network Video Recorder guide, DVR security camera systems guide, and DVR vs NVR vs Cloud DVR.
For DVR storage calculator reference data on recording bitrates and codec efficiency, consult the ITU H.264 standard, the SMPTE technical specifications, and the IEEE video engineering resources.
DVR Storage Calculator: HDD Math for CCTV, NVR, and DVR Recording
A DVR storage calculator estimates the amount of hard drive space needed for a CCTV install given camera resolution, video compression codec, frame rate, number of cameras, and days of retention. A CCTV storage calculator (sometimes called an HDD calculator, capacity calculator, or hard drive calculator) takes those five inputs and returns total storage capacity in TB. The same CCTV HDD math applies to video storage calculator tools built into NVR and DVR vendor apps: they pull camera resolution and video format from the active cameras and calculate required storage space automatically.
Sample calculation using a surveillance storage calculator: four 1080p CCTV cameras at H.265 video compression, 15 fps motion-only, 30 days retention. Video quality at 1080p with H.265 compresses roughly 2 Mbps per camera; 4 cameras × 2 Mbps × 86400 seconds × 30 days ÷ 8 bits ÷ 1024 = ~250 GB. Round up for safety margin and pick a 1TB HDD. The same math at 4K pushes storage space to 1TB per camera per month continuous. NVR and DVR storage calculator tools differ only in that an NVR processes already-compressed IP streams while a DVR does the compression itself. A security NVR with 4K cameras and NVR or DVR math at 16 channels can need 8TB+ HDDs for 30 day retention. Storage devices for CCTV surveillance default to surveillance-grade HDDs (WD Purple, Seagate SkyHawk) rated for 24/7 write cycles.
Related DVR Storage Calculator & Hardware Guides
- How Much Storage Do Security Cameras Need?. Storage planning guide
- Best DVR for Security Camera. Top systems with matching storage
- 16-Channel DVR Systems. Large-capacity DVR options
- 8-Channel DVR Recorders. Mid-range DVR picks
- H.265 vs H.264 Compression. Codec choice affects your DVR storage calculator results
- 4K vs 1080p Security Cameras. Resolution impact on storage
- Cloud vs Local Storage. Storage options comparison
- RAID Configuration Guide. Redundant storage for DVR systems
- VESA Compatibility in DVRs. Hardware mounting guide
- Install and Set Up DVR. Complete setup tutorial
- DVR Recorder Explained. Fundamentals of digital video recording
- Network Video Recorder (NVR). Modern alternative to DVR
- DVR vs NVR vs Cloud DVR. Comparison of storage technologies
- Home Security Camera DVR. Residential systems overview
- DVR Buying Guide. Choose the right system
- Best Budget DVR Security Camera Systems. Value picks