The fastest way to slow down video on iPhone

Open the Photos app, find the video you want to slow down, tap Edit, then tap the speed icon (it looks like a speedometer) in the toolbar at the bottom. Drag the slider left to make the video slower — you can choose from half speed (0.5x), three-quarter speed (0.75x), or normal speed (1x). Tap Done to save your changes.

This method works on any iPhone running iOS 13 or later and edits the video file itself, so the slow-motion version replaces the original. If you want to keep both versions, duplicate the video first by opening it in Photos, tapping the three dots, and selecting Duplicate.

The Photos app method is the simplest for casual edits. If you need more control — like slowing down only part of a video, adding effects, or exporting at different resolutions — you'll need a dedicated video editor.

Key Takeaways

  • The Photos app can slow video to 0.5x, 0.75x, or normal speed by tapping Edit and using the speed slider.
  • Editing in Photos overwrites the original video, so duplicate it first if you want to keep both versions.
  • iMovie lets you slow down specific sections of a video and export the result as a new file without changing the original.
  • Third-party apps like Adobe Premiere Rush and CapCut offer frame-by-frame speed control and more export options than the built-in tools.
  • Slowing down video uses more storage because the file size stays roughly the same but the playback duration increases.

Using iMovie for more control over which parts slow down

iMovie (free on the App Store) lets you slow down specific sections of a video instead of the whole thing. Open iMovie, tap the plus icon, select Movie, then choose your video. Tap the video in the timeline to select it, then tap the speed icon (three dots with a gauge) in the toolbar.

You can set the speed to 0.25x, 0.5x, 0.75x, 1x, 1.25x, 1.5x, or 2x. To slow down only part of the video, split the clip at the point where you want the speed change to begin. Tap and hold on the video in the timeline, then tap Split Clip. Now you have two separate clips you can set to different speeds.

When you're done, tap Done, then tap Share and choose where to save the video. iMovie creates a new file, so your original stays unchanged. The export takes longer than Photos because iMovie re-encodes the entire video.

Third-party apps for frame-by-frame speed adjustment

Adobe Premiere Rush (free with limits, paid subscription for full features) and CapCut (free) both let you adjust speed at the frame level, meaning you can create smooth transitions between different playback speeds within a single clip.

In CapCut, import your video, tap it in the timeline, then tap Speed at the bottom. You can set a base speed for the whole clip, then tap Curve to create speed changes that ease in and out smoothly rather than jumping from one speed to another. This creates a more professional look than a sudden shift.

Adobe Premiere Rush works similarly but requires a subscription ($9.99 per month) to export videos longer than one minute. Both apps save your edited video as a new file and let you choose the resolution and frame rate before exporting.

Slowing down video shot in regular mode versus slow-motion mode

If you shot your video in regular mode (not using the slow-motion camera), slowing it down in any app will make it look choppy because the phone captured fewer frames per second. A regular video shot at 30 frames per second (fps) has less visual information than a slow-motion video shot at 120 fps or 240 fps.

When you slow a 30 fps video to half speed, the app has to guess what happens between frames, which creates visible stuttering. Slow-motion videos shot at 120 fps or 240 fps have much more frame data, so slowing them down further looks smooth.

If you want to slow down a regular video and keep it looking smooth, limit the slowdown to 0.75x speed or less. For dramatic slow-motion effects, shoot in the Slow-Mo mode in the Camera app first — it captures at 120 fps by default on most iPhones.

How file size and storage change when you slow down video

Slowing down a video does not make the file smaller, even though it plays for longer. A one-minute video slowed to half speed plays for two minutes but takes up roughly the same storage space because the phone is not removing any frames — it is just playing them more slowly.

When you export a slowed video from iMovie or a third-party app, the file size may actually increase slightly because the app re-encodes the video and may use a higher quality setting. A video that was 500 MB at normal speed might become 550 MB or 600 MB when exported from iMovie at half speed.

If storage is tight, edit in Photos instead of iMovie — Photos makes the change directly to the original file without re-encoding, so the file size stays the same. Just remember that this overwrites the original, so back it up first if you might want the normal-speed version later.

Exporting slow-motion video to share or save

Videos edited in Photos stay in your Photos library and sync to iCloud if you have iCloud Photos turned on. To save a slow-motion video to your computer, open Photos on your Mac or PC, find the video, right-click it, and select Export. Choose a location and the video downloads at the resolution it was shot in.

iMovie and third-party apps give you more export options. In iMovie, tap Share, then choose Save Video to keep it in Photos, or Files to save it to a specific folder. You can also share directly to social media — iMovie will compress the video to match each platform's requirements.

If you are uploading to YouTube, Instagram, or TikTok, let the app handle the compression rather than exporting at the highest quality first. These platforms re-compress videos anyway, so exporting at full resolution wastes storage and upload time.

Frequently Asked Questions

Can I slow down only part of a video on iPhone?

Yes, but only with iMovie or a third-party app. The Photos app slows down the entire video. In iMovie, split the clip where you want the speed change to start, then set different speeds for each section.

Will a slowed-down video look blurry or choppy?

It depends on how the video was shot. Videos shot in regular mode (30 fps) will look choppy if slowed down more than 25 percent. Videos shot in slow-motion mode (120 fps or 240 fps) stay smooth even at half speed or slower.

Does slowing down video use more storage space?

No, the file size stays roughly the same. A one-minute video slowed to half speed plays for two minutes but takes up the same storage as the original. Exporting from iMovie may increase the file size slightly because it re-encodes the video.

Can I undo a slow-motion edit in Photos?

Yes. Open the video in Photos, tap Edit, tap the speed icon, and drag the slider back to 1x (normal speed). Tap Done to save. If you already saved over the original, you can restore it from Recently Deleted if you deleted it within 30 days.

What's the difference between slowing down and using slow-motion mode?

Slow-motion mode in the Camera app captures video at a higher frame rate (120 or 240 fps) while you are recording. Slowing down after recording just plays existing frames more slowly. Slow-motion mode gives you more visual information, so the result looks smoother.