• To speed up a video on your iPhone, you can use iMovie or the Photos app.
• You can adjust the speed of a video in iMovie by using the Speed button in the video editing toolbar.
• You can also speed up a Slo-mo video in Photos by dragging the vertical bars below the frame viewer.

You can adjust the speed of a video on an iPhone in two different ways, depending on the type of file you’re working with.

If you want to speed up a video that’s at regular speed, you can upload it to the free iMovie app and use its native speed tool.

If you’ve recorded a video using your iPhone’s Slo-Mo feature, open your video in the Photos app in edit mode, and play with the sliding vertical bars beneath the frame viewer.

Here’s how to do both. 

How to adjust the speed of a video on your iPhone in iMovie

1. Open the iMovie app on your iPhone. If a welcome screen appears, tap Continue.

2. A New Projects window will appear. Tap Movie.

3. On the next screen, select a video from your camera roll, then tap Create Movie at the bottom.

4. Tap the video clip in the timeline and wait for the video editing tools to appear before selecting the speed tool, which looks like a speedometer.

5. Drag the yellow slider at the bottom to the right to speed up your video or to the left to slow down your video. You can increase the speed by up to 2x the original or slow it down by up to 1/8x the original.

Quick tip: You can preview your changes by tapping the Play button in the middle of the screen.

6. Tap Done in the top-left corner of the screen.

7. Hit the Share button at the bottom of the screen and choose how you want to save the completed video.

How to speed up a Slo-mo video on your iPhone in the Photos app

1. Open the Photos app and select the Albums tab at the bottom of the screen.

2. On the Albums page, scroll down to the Media Types section and tap Slo-mo.

3. Select the video you want to speed up and tap Edit in the top-right corner.

4. In the white hatched line beneath the video timeline, drag the two taller white vertical bars together to completely remove the Slo-Mo effect and speed up the video.

5. Tap Done in the bottom-right corner.

Quick tip: You can come back to the file and use the drag bars to restore slow motion anywhere in the video.