How Long Does 128GB Last in a Security Camera?
There is no reliable answer based on resolution alone. Bitrate and recording mode drive retention.
Planning estimate: at a constant 4 Mbps, 128GB stores roughly 71 hours—about 3 days—before accounting for formatting overhead and variable bitrate.
| Average bitrate | Approx. 128GB continuous retention |
|---|---|
| 1 Mbps | About 12 days |
| 2 Mbps | About 6 days |
| 4 Mbps | About 3 days |
| 8 Mbps | About 1.5 days |
Why estimates vary
Motion-only recording can extend retention dramatically. Scene complexity, audio, frame rate and compression also change storage use. A busy sidewalk and an empty hallway will not create the same amount of footage.
The formula
Approximate storage in GB = bitrate in Mbps × seconds recorded ÷ 8 ÷ 1,000. Our storage calculator handles multiple cameras and retention days.
128GB or 256GB?
At identical settings, doubling capacity roughly doubles retention. Confirm the camera's supported card capacity and use endurance-rated media for frequent writes.
Bottom line
Size storage from bitrate, not megapixels. If long retention is mandatory across several cameras, compare microSD vs NVR.