You can slow videos down on an iPhone either in the Photos app or with iMovie.

Using the Photos app (iOS 17/18)

This works best for videos shot in Slo‑Mo, but newer iOS versions also add speed controls for regular clips.

1. Open Photos and tap the video.
2. Tap Edit (top right).
3. If you see a “Speed” or speedometer-style control, tap it.
4. Drag the slider or handles toward the turtle / lower percentage to make that section slower.
5. Tap Done to save.

Using iMovie (free Apple app)

Use this if you want more control or are on older iOS.

1. Install/open iMovie, tap Create Project → Movie.
2. Select your video and tap Create Movie.
3. Tap the clip in the timeline, then tap the speedometer icon.
4. Drag the slider left (toward the turtle / below 1x) to slow it down.
5. Tap Done, then the Share button to save the new slowed‑down video to Photos.

Recording in slow motion

For smoother slow‑mo, change how you record:

1. Go to Settings → Camera → Record Slo‑Mo.
2. Choose a higher frame rate option (like 1080p at 120 fps or 240 fps).
3. In the Camera app, choose Slo‑Mo and record; you can then fine‑tune which part is slow in Photos → Edit.