CCTV / NVR Storage Calculator
Plan how much hard drive space your IP camera system needs — by camera count, resolution, frame rate, codec, recording schedule, and retention. Supports mixed deployments where different cameras run different settings. Built by Datastrive, a Chicago managed IT and low-voltage contractor.
- Multiple camera groups
- H.264 and H.265 (HEVC)
- Drive size & RAID recommendations
Typical bitrate per camera
The single biggest driver of storage is bitrate — the data rate each camera streams at. Bitrate scales with resolution, frame rate, and codec. These are conservative averages used by the calculator above (H.264 baseline; H.265 cuts about 45% off).
| Resolution | 15 fps (H.264) | 30 fps (H.264) | 15 fps (H.265) | 30 fps (H.265) |
|---|---|---|---|---|
| 720p (1MP) | 1.5 Mbps | 3.0 Mbps | 0.8 Mbps | 1.7 Mbps |
| 1080p (2MP) | 3.0 Mbps | 6.0 Mbps | 1.7 Mbps | 3.3 Mbps |
| 4MP | 6.0 Mbps | 12.0 Mbps | 3.3 Mbps | 6.6 Mbps |
| 5MP | 8.0 Mbps | 15.0 Mbps | 4.4 Mbps | 8.3 Mbps |
| 4K (8MP) | 12.0 Mbps | 24.0 Mbps | 6.6 Mbps | 13.2 Mbps |
How to size CCTV storage in the real world
Calculators give you a starting point. Production systems need a few extra considerations — codec choice, redundancy, drive selection, and the difference between manufacturer claims and what actually happens at 2 AM in a parking lot with snow falling.
- Use H.265 (HEVC) wherever your hardware supports it H.265 cuts storage roughly in half versus H.264 at equivalent quality — the single biggest lever you have. Make sure both your cameras and your NVR support it; mismatched codecs force re-encoding which defeats the savings. Modern Hanwha, Hikvision, Dahua, and UniFi Protect cameras all support H.265 natively.
- Match frame rate to actual purpose, not “max possible” 15 fps is sufficient for most surveillance: facial recognition, license plates, evidence-quality footage. 30 fps doubles your storage for almost no operational benefit. Reserve high frame rates for specific zones — cash registers, narrow doorways — not the entire deployment.
- Use motion-triggered recording for low-traffic zones For storage rooms, server closets, and overnight loading docks, motion-triggered recording cuts storage by 60–85% with zero loss of useful footage. For high-traffic public areas, continuous is safer because motion detection occasionally misses the start of an event. Mix the two strategically.
- Always use surveillance-grade hard drives Standard desktop drives are designed for 8 hours/day of light read activity. Surveillance drives like WD Purple and Seagate SkyHawk are rated for 24/7 sustained writes from up to 64 video streams simultaneously. Using desktop drives in an NVR is the most common cause of premature drive failure in surveillance systems.
- Plan for RAID redundancy if footage matters RAID 1 mirrors two drives — simple, easy to recover, but expensive (50% capacity efficiency). RAID 5 across 4–6 drives is common in business deployments — you lose one drive’s worth of capacity but survive any single drive failure. For critical footage (evidentiary, healthcare, high-value retail), RAID 6 survives two simultaneous failures and is worth the extra drive.
- Add a 20% buffer for the reality you can’t predict Bitrates spike during storms, busy retail hours, and motion-heavy scenes. Camera firmware updates can change defaults. Extending retention from 30 to 60 days mid-year is a common ask. The calculator includes a 20% buffer in the drive recommendations — don’t strip it back to 0% just to fit a smaller drive.
- Check retention compliance for your industry Healthcare (HIPAA-adjacent), banking, cannabis dispensaries, gas stations, and many state-licensed industries have minimum video retention requirements ranging from 30 days to 2 years. Confirm yours before sizing — under-retention is a compliance issue, not just an operational one.
Frequently asked questions
Why is my actual storage usage different from this estimate?
Modern cameras almost always use variable bitrate (VBR) encoding. The bitrate goes up when the scene has motion, lighting changes, or visual complexity, and down when the scene is static. A camera pointed at an empty hallway uses far less than its rated bitrate; a camera at a busy intersection uses more.
The calculator uses conservative averages that work well across mixed environments. For an exact number, record one representative camera at your target settings for 24 hours, then check actual disk usage and multiply.
Is H.265 always better than H.264?
For storage savings, yes — about 45% smaller files at equivalent quality. The catch is compatibility: every device that touches the video stream needs H.265 support, including the camera, the NVR, browsers used for live viewing, and any export/sharing workflows. H.264 is universal; H.265 is widely-but-not-universally supported.
Modern enterprise systems (UniFi Protect, Hanwha Wisenet, Hikvision, Dahua, Avigilon) all support H.265 end-to-end. Older 2018-and-earlier deployments may have edge-case incompatibility. If you’re buying new gear, prioritize H.265.
Should I use motion-only or continuous recording?
Motion-triggered recording cuts storage dramatically (60–85% in low-traffic areas) but introduces risk: motion detection occasionally misses the start of an event, especially for slow-moving subjects, gradual changes, or when motion sensitivity is tuned conservatively to avoid false triggers.
For high-stakes recording (evidence, compliance, insurance, retail loss prevention), continuous is safer. For supplementary coverage of low-activity zones, motion-only is efficient. Most professional deployments mix the two: continuous on critical zones, motion on the rest.
What’s the difference between fps and bitrate?
Frame rate (fps) is how many images per second the camera captures. Bitrate is how much data the encoded video stream uses per second. They’re related — doubling frame rate roughly doubles bitrate — but bitrate is the actual driver of storage. You can have two cameras at the same fps with very different bitrates depending on scene complexity, codec, and quality setting.
For surveillance, 15 fps at a higher quality setting will produce better evidentiary footage than 30 fps at a lower quality setting, while using the same storage.
Do I need a RAID setup for my NVR?
Depends on what footage is for. If it’s purely operational (you might check it occasionally and don’t care if a week is lost), a single drive is fine — replace it when it fails. If footage is for evidence, compliance, insurance, or business operations, RAID 1 (mirror) is the minimum reasonable setup.
For larger deployments (16+ cameras), RAID 5 or RAID 6 on 4+ surveillance-grade drives gives you both redundancy and efficient capacity. The math: RAID 5 loses one drive’s worth of capacity to parity; RAID 6 loses two but survives two simultaneous failures.
How much storage for 30 / 60 / 90 days of footage?
Storage scales linearly with retention — 60 days needs exactly twice as much space as 30 days, all else equal. So once you’ve calculated 30 days for your camera mix above, the rest is multiplication.
Rough rule of thumb for a typical small-business deployment (8 cameras, 1080p, 15 fps, H.265, continuous): about 1.5 TB per 30 days. Scale up linearly: 3 TB for 60, 4.5 TB for 90, 9 TB for 6 months. With surveillance drives, a single 8 TB drive comfortably covers 90 days for that scenario, with headroom.
Need help designing the rest of the camera system?
Datastrive designs and installs IP camera systems across the Chicago area — from small offices and retail to multi-site warehouses. Cabling, switches with PoE budget, NVR sizing, mobile and remote viewing, and ongoing monitoring. We’re a managed IT and low-voltage contractor for small and mid-sized businesses.
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