The simplest way to slow down video on iPhone

You can slow down video on iPhone using the built-in Photos app — no separate software needed. Open the video in Photos, tap Edit, then tap the three dots and select Video. At the bottom of the screen, you'll see a speed slider that lets you choose from half speed (0.5x) up to double speed (2x). Tap Done to save your changes.

This method works on any iPhone running iOS 13 or later. The edited version saves as a new file, so your original stays unchanged. The process takes about 30 seconds once you open the video.

If you want more control — like slowing down only part of a video, or slowing it down more than half speed — you'll need to use iMovie or a third-party app. But for a quick slow-motion effect on the whole video, the Photos app is the fastest route.

Key Takeaways

  • The Photos app on any iPhone can slow down video to half speed without opening another program.
  • Edited videos save as new files, leaving your original untouched.
  • iMovie gives you more options, like slowing down just one section or choosing speeds slower than 0.5x.
  • Third-party apps like SlowMotion or Videoshop let you adjust speed frame-by-frame and add effects.
  • Slowing down video uses more storage because the file size grows when you extend the duration.

Using iMovie for more control over speed

iMovie is Apple's video editing app and comes free on most iPhones. It lets you slow down part of a video instead of the whole thing, and gives you more speed options than Photos does. Open iMovie, tap the plus sign, select Movie, then choose your video. Tap the video in the timeline at the bottom, then tap the three dots and select Speed.

You can drag the slider to any speed you want — slower than 0.5x or faster than 2x. If you only want to slow down one section, cut the video into clips first by tapping where you want the cut, then tapping the blade icon. Then explore speed to just that clip.

iMovie saves your project separately from your original video, so you can always go back and make changes. When you're done, tap Share and choose where to save it — your Photos library, Messages, or another app.

Third-party apps for frame-by-frame control

If you need precise control over which frames slow down and which stay normal, third-party apps give you tools the built-in options don't. Apps like SlowMotion, Videoshop, and FiLMiC Pro let you mark exact points in the video where speed changes happen, rather than explore one speed to a whole section.

These apps also let you add effects while you're adjusting speed — things like reverse playback, freeze frames, or slow-motion replays of specific moments. Most are paid apps or offer a free version with limited features. read from the App Store, open your video, and look for a speed or timeline tool in the menu.

The trade-off is that these apps take longer to learn and use than Photos or iMovie. They're worth it if you're editing video regularly or need effects beyond basic speed changes.

Why slowing down video takes more storage space

When you slow down a video, the file size grows because you're stretching the same content across more time. A 10-second video slowed to half speed becomes 20 seconds long. Your iPhone has to store all those extra frames, even though they're duplicates of the original ones.

A typical iPhone video uses about 100 to 150 megabytes per minute at standard quality. If you slow a 1-minute video to half speed, it becomes 2 minutes and takes up roughly double the storage. Before you slow down a long video, check how much free space you have — go to Settings, tap General, then iPhone Storage.

If storage is tight, consider deleting the original after you've confirmed the slowed version looks right. You can also lower the video quality before slowing it down to save space, though this makes the final video look grainier.

Slowing down video that was shot in slow motion

If your video was already shot in slow-motion mode (the 120fps or 240fps setting on newer iPhones), slowing it down further can make it look choppy or unnatural. Slow-motion footage already has more frames per second than normal video, so stretching it more creates visible gaps.

Instead, try playing it at normal speed or slightly slower. Open the video in Photos, tap Edit, then adjust the speed slider to see what looks smooth. You may find that the original slow-motion speed is already what you want.

If you do need to slow it down more, iMovie or a third-party app will do it, but the result may not look as fluid as slowing down normal-speed video. Test with a short clip first to see if the effect works for what you're trying to do.

Exporting and sharing your slowed-down video

Once you've slowed down your video, you need to save it somewhere you can use it. In Photos, the edited version automatically saves to your library. In iMovie, tap Share and choose Photos to save it to your library, or pick another app like Messages, Mail, or a cloud service.

If you want to share it online — to social media, email, or a messaging app — iMovie and third-party apps let you export directly. The file size matters here: a slowed-down video is larger and takes longer to upload. If the upload keeps failing, try lowering the resolution before you export. Most apps have a quality or resolution setting in the export menu.

For the fastest upload, use WiFi instead of cellular data. A 2-minute slowed-down video can be 300 to 500 megabytes, which takes several minutes on a typical mobile connection.

Troubleshooting common slow-motion problems

If the slowed-down video looks jerky or stutters, the original video may have been shot at a low frame rate or in poor lighting. Low frame rate means fewer individual images per second, so when you stretch them out, the gaps become visible. Try slowing it down less, or use a different video.

If the audio sounds wrong — too deep, distorted, or out of sync — this is normal when you slow video. Most apps slow the audio along with the video, which makes it sound lower-pitched. Some apps let you keep the audio at normal speed while the video slows down. Check the settings in iMovie or your third-party app for an audio option.

If you can't find the speed tool in Photos, make sure you're running iOS 13 or later. Go to Settings, tap General, then Software Update to check your version. Older iPhones may not support this feature.

Frequently Asked Questions

Can I slow down just the audio without slowing the video?

The built-in Photos and iMovie apps slow both together. Some third-party apps like FiLMiC Pro let you adjust audio and video speed separately, but this is an advanced feature. For most uses, keeping them together looks and sounds more natural.

What's the slowest speed I can make a video?

Photos and iMovie let you go down to 0.5x (half speed). Third-party apps often go slower — some let you slow to 0.25x or even 0.1x. The slower you go, the more storage the file takes up and the more likely it will look choppy if the original video wasn't shot at high frame rate.

Does slowing down video reduce the quality?

Slowing down doesn't reduce quality by itself — you're just stretching the same frames over more time. However, if the original video was shot in low light or at low resolution, those problems become more obvious when you slow it down because you're looking at each frame longer.

Can I undo the slow-motion effect after I save it?

In Photos and iMovie, yes — tap Edit again and move the speed slider back to 1x. If you exported the video to another app or shared it, you'll need to re-edit the original. This is why it's good to keep your original video untouched.

Why does my slowed-down video have a weird sound?

When you slow video, the audio pitch drops along with the speed. A video slowed to half speed has audio that sounds like a deep, slow voice. This is normal. If you don't want this effect, some apps let you mute the audio and add music or a voeover instead.