The Five-Minute “Back-of-Envelope” Storage Formula
Storage (GB)=Bitrate (Mb/s)×0.54×Hours per day×Days ext{Storage (GB)} = ext{Bitrate (Mb/s)} imes 0.54 imes ext{Hours per day} imes ext{Days}Storage (GB)=Bitrate (Mb/s)×0.54×Hours per day×Days
Where 0.54 converts megabits-per-second into gigabytes-per-hour.
Example: 10 indoor 4 K cameras
- Bitrate: 4 Mb/s each
- Hours: 24
- Days: 30
4×0.54×24×30=1,555 GB per camera4 imes 0.54 imes 24 imes 30 = 1,555 ext{ GB per camera}4×0.54×24×30=1,555 GB per camera
Ten cameras × 1,555 GB = 1.55 TB total. Add a 20 % safety margin for disk formatting and metadata, and you need a 2 TB drive set. Small, isn’t it? Compression really earns its keep.
Example: 20 outdoor cameras at 6 Mb/s, 45 days
6×0.54×24×45=3,499 GB per camera6 imes 0.54 imes 24 imes 45 = 3,499 ext{ GB per camera}6×0.54×24×45=3,499 GB per camera
Twenty cameras × 3.5 TB ≈ 70 TB. Here we step into multi-bay NVR territory or a NAS/SAN array.
If you prefer a visual tool, our sales team use a simple Excel sheet—contact us and we’ll send you a copy, no strings attached.
Quick Reference Table
| Cameras | Bitrate (Mb/s) | Days | Approx. Storage Needed |
| 8 × office domes | 4 | 30 | ~ 1 TB |
| 16 × retail shop | 4 | 60 | ~ 4 TB |
| 24 × car park bullets | 6 | 45 | ~ 24 TB |
| 32 × mixed indoor/outdoor | 6–8 | 90 | 50–60 TB |
(Numbers rounded; include 20 % extra for overhead and RAID redundancy.)
Understanding Network Load
Peak vs Average
Peak load is what your switch sees when all cameras send full bitrate at once—think 8 AM shift change.
Average load smooths over 24 hours. Design for peak; average looks after itself.
Total Peak (Mb/s)=Number of cameras×Bitrate ext{Total Peak (Mb/s)} = ext{Number of cameras} imes ext{Bitrate}Total Peak (Mb/s)=Number of cameras×Bitrate
A 24-camera warehouse at 6 Mb/s peaks at 144 Mb/s—well within a 1 Gb Ethernet uplink, but remember other traffic (Wi-Fi, VoIP) rides on that pipe too. Segregating CCTV to its own VLAN keeps jitter out of phone calls.
PoE Budget
Check the switch’s total PoE watts. A 4 K camera with IR LEDs draws about 12 W; thirty of those need 360 W. A typical 24-port PoE+ switch supplies 370 W—tight but workable. Add lighting or pan-tilt motors and you may need a second switch or mid-span injector.
