CCTV / NVR Storage Calculator
Calculate CCTV / NVR storage and bandwidth. Add IP cameras by resolution and codec (H.264/H.265) to get the hard drive size in TB for your retention days, plus the total network bandwidth. Free, no sign-up.
What to calculate next
Tools commonly used alongside this calculation
PoE Power Budget Calculator
Check a PoE switch power budget per IEEE 802.3af/at/bt. Add powered devices by type and PD class to total the watts drawn, see the utilization and headroom, and confirm the load fits the switch budget and port count. Free, no sign-up.
Fiber Optic Loss Budget Calculator
Calculate a fiber optic link loss budget per TIA-568 and FOA. Add fiber length, connectors, and splices to total the cable plant loss in dB, then compare it to the transceiver power budget for the link margin and pass/fail. Free, no sign-up.
CCTV Lens & FOV Calculator
Calculate CCTV camera field of view and DORI distances. Enter sensor format, resolution, and lens focal length to get HFOV/VFOV angles and Detect, Observe, Recognize, and Identify ranges in feet per EN/IEC 62676-4. Free, no sign-up.
Explanation
A CCTV storage calculator tells you how big an NVR hard drive needs to be to hold a set number of days of footage, and how much network bandwidth the cameras add up to. Storage is driven almost entirely by the recorded bitrate of each camera — the resolution, frame rate, and codec only matter because they set that bitrate. This tool is vendor-neutral: enter any camera’s configured bitrate, or start from a typical value by resolution and codec, and it sizes the drive in terabytes.
How storage is calculated
Storage scales linearly with bitrate, recording time, camera count, and retention. The key constant is that a 1 Mbps stream records about 0.45 GB per hour, so a camera running continuously uses roughly 10.8 GB per day per Mbps.
Storage (GB) = Σ [ bitrate × 0.45 × (hours/day × motion) × cameras ] × days
Bandwidth (Mbps) = Σ ( bitrate × cameras )
| Term | Meaning |
|---|---|
| bitrate | Recorded stream rate per camera (Mbps) |
| hours/day | Hours each camera records per day (max 24) |
| motion | Recording-mode duty factor (1.0 continuous, less for motion) |
| days | Retention — days of footage kept |
GB and TB here are decimal (1 TB = 1000 GB) to match how drives are labeled. The aggregate bandwidth is the peak recording throughput the NVR and switch must handle — useful when you also size the fiber uplink carrying the camera traffic back to the head end.
Typical bitrates and recording modes
These are starting points for medium quality at roughly 15–20 fps with H.265. H.264 needs about 1.8× the bitrate for the same picture, so switching to H.265/H.265+ nearly halves storage. Always confirm against the bitrate your camera is actually set to.
H.265 bitrate by resolution
| Resolution | Typical H.265 bitrate |
|---|---|
| 1 MP (720p) | 1 Mbps |
| 2 MP (1080p) | 2 Mbps |
| 3 MP | 3 Mbps |
| 4 MP | 4 Mbps |
| 5 MP | 5 Mbps |
| 8 MP (4K) | 8 Mbps |
| 12 MP | 10 Mbps |
Recording modes
| Mode | Duty factor |
|---|---|
| Continuous | 1.00 |
| Light motion (70%) | 0.70 |
| Motion / event (40%) | 0.40 |
Motion-only recording savings vary widely with scene activity — a busy entrance saves little, a quiet storeroom saves a lot. Treat the duty factors as planning estimates, not guarantees.
Notes and limitations
This is a planning estimate. Real footage size swings with scene complexity, lighting, motion, and variable-bitrate encoding, so add margin and use surveillance-rated drives (WD Purple, Seagate SkyHawk) built for continuous multi-stream writes. Usable drive capacity is also a few percent below the label after formatting.
Storage and power are the two questions on every camera install. Once you know the cameras, the PoE power budget calculator checks that the switch can power them all per IEEE 802.3af/at/bt.