CCTV storage calculator
Estimate for continuous recording. Actual usage depends on camera model, scene and settings.
The hard disk in a CCTV recorder (NVR for IP cameras, DVR for analog HD cameras) decides how many days of footage you keep. Enter your cameras above to see the storage you need, or choose the disk you already have to see how many days it will record.
How the calculation works
Storage per camera per day = bitrate (Mbps) × 3,600 seconds × recording hours ÷ 8 (to convert bits to bytes). Multiply by the number of cameras and the number of days you need to keep.
For example, one camera at 4 Mbps recording 24 hours uses about 43 GB a day. Sixteen such cameras kept for 30 days need about 21 TB.
To go the other way (how many days a disk records): days = disk size ÷ (storage per camera per day × number of cameras). The calculator keeps about 7% aside, because a “1 TB” disk shows a little less usable space once it is formatted in the recorder.
Typical recording days (24-hour continuous recording, after formatting)
| Cameras and setting | 1 TB | 2 TB | 4 TB | 8 TB |
|---|---|---|---|---|
| 4 cameras, 2MP H.265 (about 1 Mbps) | about 21 days | about 43 days | about 86 days | about 172 days |
| 4 cameras, 2MP H.264 (about 2 Mbps) | about 10 days | about 21 days | about 43 days | about 86 days |
| 8 cameras, 4MP H.265 (about 2 Mbps) | about 5 days | about 10 days | about 21 days | about 43 days |
| 16 cameras, 4MP H.264 (about 4 Mbps) | about 1 day | about 2 days | about 5 days | about 10 days |
Real numbers depend on the camera, the scene and the recorder settings. Motion recording at night or in quiet areas can stretch these days a lot.
How many TB for 30 days?
Worked out with the same formula as the calculator above: 24-hour continuous recording, 30 days kept, and about 10% spare space when choosing disks.
| Cameras | 2 Mbps per camera (2MP H.264 / 4MP H.265) | 4 Mbps per camera (4MP H.264) |
|---|---|---|
| 4 cameras | about 2.6 TB (1 × 4 TB) | about 5.2 TB (2 × 4 TB) |
| 8 cameras | about 5.2 TB (2 × 4 TB) | about 10.4 TB (3 × 4 TB) |
| 16 cameras | about 10.4 TB (3 × 4 TB) | about 20.7 TB (6 × 4 TB) |
| 32 cameras | about 20.7 TB (6 × 4 TB) | about 41.5 TB (8 × 6 TB) |
Check that your NVR has enough disk bays for the suggested number of disks. Motion recording, H.265 and lower frame rates can cut these figures a lot.
Recorder and camera prices are on the CCTV price list (4, 8 and 16 camera sets with DVR/NVR), with separate tables for dome camera price and 4 channel DVR price, for example the CP Plus 4 channel DVR and 8 channel DVR. For a site plan with the right disk size, see CCTV installation in Gurgaon.
What changes the bitrate
- Resolution: higher resolution needs a higher bitrate.
- Compression: H.265 usually needs much less storage than H.264 for similar quality.
- Scene activity: busy roads, trees moving in the wind and night noise increase bitrate.
- Frame rate: fewer frames per second lowers storage.
Ways to save storage
- Use H.265 or smart codecs where your cameras and recorder support them.
- Record on motion for low-activity areas such as stores and back gates.
- Use a lower frame rate where smooth motion is not needed.
- Keep high quality on the few cameras that matter most (gate, cash counter) and a lower bitrate elsewhere.
Choosing the hard disk
Use surveillance-rated hard disks made for 24-hour writing, not desktop disks. Check how many disk bays your NVR or DVR has and the largest disk size it supports. See our 1 TB, 2 TB and 4 TB surveillance hard disks, and the CCTV price list for cameras and recorders. Many sites in Delhi NCR keep 30 days of footage; if a rule, insurer or your own policy asks for a set number of days, size the disk for that number.
These figures are estimates. We size storage exactly during the design stage of every CCTV installation.
Frequently asked questions
How many days will a 1 TB hard disk record for 4 cameras?
With four 2MP cameras on H.265 recording 24 hours a day, about 3 weeks. On H.264 it is about 10 to 12 days. Motion recording can make it last longer.
How do I calculate CCTV hard disk size?
Bitrate (Mbps) x 3,600 x recording hours / 8 gives MB per camera per day. Multiply by cameras and by the days you want to keep. The calculator on this page does it for you.
Is a normal computer hard disk fine for an NVR?
It is better to use a surveillance-rated hard disk. It is built to write video 24 hours a day and usually lasts longer in a recorder.
NVR or DVR: does the storage calculation change?
No, the formula is the same. What changes is the bitrate: IP cameras on an NVR and analog HD cameras on a DVR use different bitrates for the same resolution.
How many TB do I need for 16 cameras for 30 days?
At about 4 Mbps per camera (4MP H.264) with 24-hour recording, 16 cameras need about 20.7 TB for 30 days. With H.265 at about 2 Mbps, about 10.4 TB is enough.
How many TB for 8 CCTV cameras for 30 days?
About 5.2 TB at 2 Mbps per camera or about 10.4 TB at 4 Mbps per camera, for 24-hour continuous recording.
Our engineers can visit your site and recommend the right option. Call +91 97119 00801 or request a quote.
