CCTV & Security
CCTV Storage: How Many Days of Recording Does Your Hard Drive Hold?
Short answer
Storage depends on the number of cameras, bitrate, hours recorded and days kept. As a rough guide, a 4 MP camera on H.265 at about 4 Mbps recording continuously uses roughly 43 GB per day. Four such cameras need about 170 GB a day, so a 4 TB drive holds roughly three weeks. Motion recording or lower bitrates stretch this further.
The formula
Storage per day (GB) ≈ bitrate (Mbps) × 0.45 per camera for 24 hours of continuous recording. For example, 4 Mbps × 0.45 ≈ 1.8 GB per hour × 24 ≈ 43 GB per day.
Multiply by the number of cameras and the number of days you want to keep.
Example: 4 cameras at 4 Mbps, continuous
| Hard drive | Approx. days of recording |
|---|---|
| 1 TB | ~5 days |
| 2 TB | ~11 days |
| 4 TB | ~23 days |
| 8 TB | ~46 days |
Illustrative figures that use roughly 170 GB per day for four cameras; usable space is somewhat less than the label. Real bitrates vary with scene, frame rate and settings.
Ways to stretch storage
- Use H.265 compression instead of H.264.
- Record on motion, with continuous recording on key cameras only.
- Lower the frame rate or bitrate on low-priority cameras.
- Use surveillance-rated hard drives built for constant writing.
- Add a second drive or a larger recorder.
How long should you keep footage?
Many homes keep 14 to 30 days. Businesses with compliance or dispute risks often keep longer. Decide first, then size the drive.
Common questions
What hard drive should I use?
A surveillance-rated drive, designed for constant recording, rather than a standard desktop drive.
What happens when the disk is full?
Most recorders overwrite the oldest footage automatically.
Does higher resolution use more storage?
Yes. More pixels generally means a higher bitrate, so more storage per day.