Slow-motion video
Also known as: slo-mo, slow mo video, high frame rate video
Slow-motion video records at a very high frame rate — often 120 or 240 fps — so it can be played back slowly while staying smooth. Capturing so many frames per second makes slo-mo clips large for their length.
- Records at high frame rates like 120 or 240 fps
- Large for its length because of the extra frames
- Short clips can rival much longer normal video in size
How slow motion is captured
A normal video plays at the rate it was recorded. Slow motion records far more frames per second — commonly 120 fps or 240 fps — then plays them back at a normal speed, stretching a moment over several seconds without looking choppy.
On iPhone, slow-motion mode lives in the Camera app next to Video and Photo. The higher the fps, the more dramatic the slowdown and the more frames the camera writes to storage.
Why it matters for storage
Because slow motion captures several times more frames than standard video, even short clips contain a lot of data. A brief slo-mo recording can rival a much longer normal clip in size.
If your library is filling up, slow-motion clips are worth reviewing first: they are large, often experimental, and frequently kept long after the moment has passed. Compressing or trimming them recovers meaningful space.