How Long Does a 256GB Card Last in a Security Camera?
Estimate 256GB security-camera retention for 1080p, 2K and 4K recording using bitrate and recording mode.
A 256GB microSD card can store a few days or several weeks of footage depending on bitrate and how often the camera records. Resolution alone is not enough to answer the question.
Continuous recording examples
| Average bitrate | Approximate daily use | 256GB retention before overhead |
|---|---|---|
| 1 Mbps | 10.8 GB/day | ~23.7 days |
| 2 Mbps | 21.6 GB/day | ~11.9 days |
| 4 Mbps | 43.2 GB/day | ~5.9 days |
| 6 Mbps | 64.8 GB/day | ~4.0 days |
| 8 Mbps | 86.4 GB/day | ~3.0 days |
Actual usable capacity is lower than the marketed capacity, and variable bitrate can move the result in either direction. Treat the table as planning math rather than a guarantee.
Motion recording changes everything
If a camera only saves events for 15% of the day, the same card can theoretically retain roughly six to seven times as many calendar days as continuous recording. A busy street, tree branches and insects can make real motion duty cycle far higher than expected.
Endurance matters
Continuous video repeatedly writes and overwrites the card. For cameras that record 24/7, use storage designed for sustained surveillance writes rather than choosing only by capacity.
Model any card size using the storage calculator.