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CCTV storage calculator
The hard disk size your CCTV needs, and how many days of recording any disk will hold. Four simple questions, no technical settings.
How many days will 1 TB record?
With four 2MP cameras recording all day on H.265, a 1 TB disk keeps about 21 days of footage. With motion recording, about 42 days. On an older H.264 recorder, about 10 days.
1 TB disk, 2MP cameras, recording 24 hours on H.265 at 15 fps.
CCTV recording days by hard disk size
Days of footage for each disk size and number of cameras, recording all day on H.265. Motion recording roughly doubles every figure; H.264 halves it.
2MP (Full HD) cameras: about 11 GB per camera per day
| Cameras | 500 GB | 1 TB | 2 TB | 4 TB | 8 TB |
|---|---|---|---|---|---|
| 1 | 42 | 83 | 167 | 333 | 365+ |
| 2 | 21 | 42 | 83 | 167 | 333 |
| 4 | 10 | 21 | 42 | 83 | 167 |
| 8 | 5 | 10 | 21 | 42 | 83 |
| 16 | 2.5 | 5 | 10 | 21 | 42 |
| 32 | 1.5 | 2.5 | 5 | 10 | 21 |
4MP (2K) cameras: about 22 GB per camera per day
| Cameras | 500 GB | 1 TB | 2 TB | 4 TB | 8 TB |
|---|---|---|---|---|---|
| 1 | 21 | 42 | 83 | 167 | 333 |
| 2 | 10 | 21 | 42 | 83 | 167 |
| 4 | 5 | 10 | 21 | 42 | 83 |
| 8 | 2.5 | 5 | 10 | 21 | 42 |
| 16 | 1.5 | 2.5 | 5 | 10 | 21 |
| 32 | <1 | 1.5 | 2.5 | 5 | 10 |
5MP (3K) cameras: about 32 GB per camera per day
| Cameras | 500 GB | 1 TB | 2 TB | 4 TB | 8 TB |
|---|---|---|---|---|---|
| 1 | 14 | 28 | 56 | 111 | 222 |
| 2 | 7 | 14 | 28 | 56 | 111 |
| 4 | 3.5 | 7 | 14 | 28 | 56 |
| 8 | 1.5 | 3.5 | 7 | 14 | 28 |
| 16 | <1 | 1.5 | 3.5 | 7 | 14 |
| 32 | <1 | <1 | 1.5 | 3.5 | 7 |
8MP (4K) cameras: about 43 GB per camera per day
| Cameras | 500 GB | 1 TB | 2 TB | 4 TB | 8 TB |
|---|---|---|---|---|---|
| 1 | 10 | 21 | 42 | 83 | 167 |
| 2 | 5 | 10 | 21 | 42 | 83 |
| 4 | 2.5 | 5 | 10 | 21 | 42 |
| 8 | 1.5 | 2.5 | 5 | 10 | 21 |
| 16 | <1 | 1.5 | 2.5 | 5 | 10 |
| 32 | <1 | <1 | 1.5 | 2.5 | 5 |
Using this chart?
You are welcome to use these figures on your own site, in a quote or in a class. Please link back to this page so readers can run their own numbers.
<a href="https://itnextcomputers.in/tools/cctv-storage-calculator/">CCTV storage calculator and chart</a> by ITnext Computers & CCTV Solutions How the calculator works out storage
The same three steps an installer uses, with the numbers shown so you can check them.
- Bitrate per camera. We start from the usual recorder setting for each camera quality at 15 frames a second: 2 Mbps for 2MP, 4 Mbps for 4MP, 6 Mbps for 5MP and 8 Mbps for 4K on H.264. H.265 needs about half that.
- Storage per day. Mbps × 10.8 gives GB per camera for a full day (Mbps × 3,600 seconds × 24 hours ÷ 8 bits ÷ 1,000). Motion recording is taken as 50% of the day.
- Days on a disk. We use 90% of the disk's size, because recorders format the disk and keep some space aside, then divide by what all the cameras record in a day.
Bitrate per camera at 15 fps. Storage is per camera recording all day on H.265.
| Camera | H.264 | H.265 | GB a day | GB a month |
|---|---|---|---|---|
| 2MP | 2 Mbps | 1 Mbps | 11 | 324 |
| 4MP | 4 Mbps | 2 Mbps | 22 | 648 |
| 5MP | 6 Mbps | 3 Mbps | 32 | 972 |
| 8MP | 8 Mbps | 4 Mbps | 43 | 1,296 |
A camera recording a busy road, rain or a noisy night picture uses more; a quiet storeroom uses less. If you know your camera's bitrate, enter it under "Settings for installers".
Four things that catch people out
A 4 TB drive is not 4 TB
Once the recorder formats it, about 3.6 TB is left for footage. Every quote you compare should be counting the same way.
Ask for days, not gigabytes
"One terabyte" tells you nothing on its own. "Twenty days with all four cameras recording" tells you everything.
Surveillance drives, not desktop ones
A recorder writes all day for years. A desktop drive is not built for that and fails earlier doing it.
Motion recording saves less on a busy view
A camera facing a road records almost all day anyway, and motion recording can miss the first second while it triggers.
CCTV storage questions
How many days will a 1 TB hard disk record CCTV?
With four 2MP cameras recording all day on H.265, about 21 days. On an older H.264 recorder it is about 10 days, and with motion-only recording about 42 days. Fewer cameras or motion recording stretch it further; 4K cameras cut it to roughly a quarter.
How much storage does one CCTV camera use per day?
Recording all day on H.265, a 2MP camera uses about 11 GB a day, a 4MP camera about 22 GB and a 4K (8MP) camera about 43 GB. On H.264, double those figures.
Is a 500 GB hard disk enough for 4 cameras?
For four 2MP cameras recording all day on H.265, a 500 GB disk keeps about 10 days. That is fine if you only need to check last week. If you want a month, fit a 2 TB disk.
What size hard disk do I need for 8 cameras for 30 days?
Eight 2MP cameras recording all day on H.265 need about 2.9 TB for 30 days, so a 4 TB surveillance disk. With 4MP cameras, plan for 8 TB.
Does H.265 really halve the storage?
For the same picture, H.265 needs roughly half the bitrate of H.264, so the same disk holds about twice as many days. Most DVRs and NVRs sold since 2019 support it; check that it is switched on.
What happens when the CCTV hard disk is full?
The recorder overwrites the oldest footage first and keeps recording, so the disk never "stops". The days figure tells you how far back you can go. Copy anything important to a pen drive or your phone before it is overwritten.
Does motion recording save storage?
Yes, usually by about half on an average home or shop, which is what this calculator assumes. A camera facing a busy road records almost all day anyway and saves very little, and motion recording can miss the first second of an event.
Want the disk sized for your actual site?
We survey the property, size the disk for the days you want and put the recording days on the written quote. Free, with no obligation.