This CCTV storage calculator estimates how much hard drive space your security cameras need, or how many days of footage a given drive will hold, from camera count, resolution, codec, frame rate and recording hours. It is for homeowners, small businesses and installers sizing an NVR or DVR before they buy disks.
Enter cameras, frame rate and days to keep to see results. If you leave the bitrate blank, the calculator estimates it from resolution, codec and frame rate (main stream, scaled from 30 fps); type the bitrate your recorder actually shows for the best estimate. If you leave recording hours blank, it uses 24 (continuous). Storage uses decimal units (1 TB = 1,000 GB), the way drives are sold. Smart codecs, motion recording and busy scenes change real usage.
How the CCTV Storage Calculator Works
Every camera streams video at a bitrate, measured in megabits per second. Multiply that rate by the seconds it records each day and you know how much data one camera writes; multiply by the number of cameras and the days you want to keep, and you have the drive size. The cctv storage calculator does exactly that. Resolution, codec and frame rate produce a sensible bitrate if you leave that field blank; a bitrate you type always takes priority.
Formula: Estimated bitrate = Base bitrate for the resolution × Codec factor (H.264 = 1, H.265 = 0.5) × (fps ÷ 30). GB per camera per day = Bitrate (Mbps) × Hours × 3,600 ÷ 8 ÷ 1,000. Total TB = GB per camera per day × Cameras × Days ÷ 1,000. Days on drive = Drive TB × 1,000 ÷ (GB per camera per day × Cameras), rounded down.
- Cameras — how many channels record to the same recorder.
- Resolution — sets a base bitrate at 30 fps in H.264: 2 Mbps for 720p, 4 for 1080p, 6 for 4MP, 8 for 5MP and 16 for 4K.
- Codec — H.265 is assumed to need about half the bitrate of H.264 for similar quality.
- Frame rate — frames per second; the estimate scales in proportion.
- Bitrate per camera — optional. If you leave it blank, the calculator uses the estimate from the three settings above; copy the real figure from your NVR’s stream settings when you can.
- Recording hours per day — 24 for continuous recording, which the calculator uses if you leave it blank, or fewer to approximate motion-only recording.
- Days to keep — how much history you want before old footage is overwritten.
- Drive size — optional; the installed capacity, used to show how many days it holds.
Example Scenarios
| Setup | Bitrate | Per camera per day | Total storage |
|---|---|---|---|
| 4 × 4MP, H.265, 15 fps, 24 h, 30 days | 1.5 Mbps | 16.2 GB | 1.94 TB |
| 8 × 1080p, H.264, 30 fps, 24 h, 14 days | 4 Mbps | 43.2 GB | 4.84 TB |
| 2 × 4K, H.265, 20 fps, 12 h, 30 days | 5.33 Mbps | 28.8 GB | 1.73 TB |
| 16 × 4MP, H.265, 15 fps, 24 h, 30 days | 1.5 Mbps | 16.2 GB | 7.78 TB |
| 6 × 5MP, H.264, 10 fps, 8 h, 60 days | 2.67 Mbps | 9.6 GB | 3.46 TB |
How Much Storage for Security Cameras: Tips
How much storage for security cameras you need depends far more on bitrate than on the resolution label. Two 4MP cameras from different brands can stream at very different rates. Use the cctv storage calculator with the numbers your recorder shows, and treat the built-in bitrate estimates as a rough guide.
- Read the real bitrate. Hikvision, Dahua, CP Plus and most other NVRs list the main-stream bitrate in their video settings. Constant bitrate makes the estimate reliable; variable bitrate swings with scene activity.
- 4MP camera storage per day at 1.5 Mbps is about 16 GB. Double the bitrate and you double the storage.
- Motion recording saves space, but enter honest hours. A busy street can trigger recording most of the day.
- Leave headroom. Use an nvr hard drive size calculator result as a minimum and buy the next drive size up.
- Check retention rules. Some workplaces, landlords or local laws limit how long footage may be kept; a cctv days of recording calculator only tells you what fits, not what is allowed.
H.265 roughly halves the bitrate of H.264 for similar image quality, which is why it is preselected here. To understand how the codec achieves that, see Wikipedia’s article on High Efficiency Video Coding (H.265).
CCTV Storage Calculator FAQ
How much storage does a 4MP camera use per day?
It depends on the bitrate. At 1.5 Mbps, typical for 4MP in H.265 at 15 fps, one camera writes about 16.2 GB per day when recording continuously. In H.264 at 30 fps it might stream around 6 Mbps, which is about 65 GB per day. Check your recorder’s settings for the real figure.How many days will a 4TB drive record?
Divide 4,000 GB by your daily total. Four 4MP cameras at 1.5 Mbps write about 64.8 GB a day, so a 4TB drive holds roughly 61 days. Eight 1080p cameras in H.264 at 4 Mbps write about 345.6 GB a day, which fills the same drive in about 11 days.Does the CCTV storage calculator work for Hikvision and Dahua?
Yes. The math is brand-neutral. Open the camera’s video or encoding settings in the NVR, note the main-stream bitrate, and type it into the bitrate field of the cctv storage calculator. That figure gives a far better estimate than a resolution preset because every brand tunes its encoders differently.Is H.265 worth using for storage?
Usually yes. H.265 typically needs around half the bitrate of H.264 for similar picture quality, so the same drive holds roughly twice as many days. The trade-off is higher processing load and compatibility; older recorders or viewing software may not decode it, so check your system supports it.Why does my recorder fill faster than the estimate?
Variable bitrate streams climb when scenes are busy, at night with noise, or in rain and wind. Audio recording, substreams saved to disk and higher I-frame rates also add data. Measure a few days of real usage, then adjust the bitrate in the calculator to match what your recorder actually writes.Should I size storage in TB or TiB?
Drive makers sell capacity in decimal terabytes, where 1 TB equals 1,000 GB, and this tool uses the same units. Operating systems often report binary units, so a 4 TB drive may show as about 3.64 TiB. Leave roughly 10% spare capacity for file system overhead and safety.Related Calculators
Converting between GB, TB and TiB? The data storage converter for bytes, GB and TB handles every unit. If you are setting up cameras on their own network, the subnet calculator for IP address ranges helps plan addressing, and the electricity cost calculator shows what an always-on NVR adds to your bill. Use them with the cctv storage calculator to plan the whole system.