Speed Video on iPhone: How to Slow or Speed Up Clips

Updated 5 November 2026 · Standard formula, shown below

To change a video’s playback speed on an iPhone, use the built-in Photos editor when its speed controls are available, or use iMovie for more control over a clip’s pace. The right method depends on whether you want slow motion, a faster time-lapse-style edit, or simply to watch a video faster without changing the saved file.

Choose the right kind of speed change

“Speed video” can mean two different things: changing how quickly a clip plays in a finished video, or changing playback speed temporarily while watching. These are not the same. Editing a clip alters the video you export; a playback control in a player, when available, only affects viewing.

Slow motion: Makes action play more slowly. It works best with footage recorded at a high frame rate, such as a slow-motion recording.
Speed up: Makes the clip shorter and its action appear faster. This is useful for a process, walk, or other footage where detail is less important.
Faster viewing: Changes playback temporarily, if the app offers a speed option, without creating a new edited video.

Apple’s editing controls can vary by iPhone model, iOS version, and the kind of video. If you do not see a speed control in Photos, iMovie is a practical built-in alternative for making a sped-up or slowed-down export.

Change speed in Photos

Start by checking whether the video has editable speed controls in Photos. This is especially relevant for videos recorded using the iPhone’s Slo-mo mode; ordinary footage may not expose the same controls.

Open Photos and select the video.
Tap Edit.
Look for the speed or slow-motion controls in the editing interface. On a Slo-mo video, the timeline can show where the slow-motion portion begins and ends.
Adjust the handles or available controls to choose which part plays slowly, then preview the result.
Tap Done to save the edit.

In a Slo-mo clip, adjusting the slow-motion section changes where the recording plays at its slower rate; it does not turn every ordinary video into high-frame-rate footage. If the controls shown on your phone differ, check the current iPhone user guide or try iMovie rather than assuming that a missing control means the video is damaged.

Speed up or slow down a clip in iMovie

For a straightforward speed adjustment to a saved clip, iMovie provides a timeline editor. You can set a selected segment faster or slower and export a new video. Exact labels and controls may shift between app versions, but the basic workflow is to add a clip to a project, select it, and adjust its speed.

Open iMovie, create a movie project, and add the video from your Photos library.
Tap the clip in the timeline so its editing controls appear.
Tap the speed control, usually represented by a speedometer, and move the slider toward the faster or slower setting.
Preview the section. If you only want part of the video changed, split or trim the clip first, then adjust the desired segment.
When satisfied, tap Done, then use the share or export option to save the finished movie to Photos.

A faster setting shortens the selected segment; a slower setting lengthens it. The precise range of speeds depends on the app and source footage. If the result looks uneven, try a smaller change or use footage recorded at a higher frame rate for slow motion.

What happens to sound and video quality?

Changing speed affects the timing of both picture and sound unless the editor provides separate audio controls. At a faster speed, speech and other sounds may become difficult to understand or sound unnaturally high. At a slower speed, audio can become lower or stretched. For a clean result, mute the original sound, detach or replace the audio where the app allows it, or add music that suits the new duration.

Slow motion also has a practical limit. A normal-rate recording does not contain extra frames that were never captured, so slowing it substantially can make movement appear choppy or repeated. High-frame-rate footage gives an editor more recorded frames to spread across a longer duration. Lighting matters too: high frame rates can require more light, and dim footage may look noisy or dark.

Speed changes may also affect file size after export. A shorter sped-up clip is not necessarily a smaller file, because resolution, frame rate, compression, and export settings matter. Keep the original if you may want to revise the edit later.

Common problems and fixes

No speed control in Photos: The selected video may be ordinary footage, or the control may not be offered in that editing view. Try iMovie for a general speed adjustment.
The clip looks jerky when slowed: Use less slowdown or start with high-frame-rate footage. Slowing ordinary video cannot add genuine captured detail.
The sound is distorted: Mute or replace the audio, or keep the original clip at normal speed where speech matters.
The change affects too much of the video: Split the clip into sections before adjusting speed, then preview the joins between them.
The edited version is hard to find: Check Photos for the exported movie and confirm the export completed. Keep the original until you have verified the new file.

Saving edits and keeping the original

Photos edits are generally designed to be reversible within the app: you can reopen an edited item and use its editing controls to change or revert the adjustment, where supported. An exported movie from iMovie is a separate file, so it does not replace the original unless you choose to delete the source yourself.

Before sharing, play the exported version from beginning to end. Check that the intended section changes speed, the sound is acceptable, and the clip has not been trimmed accidentally. If storage is tight, remember that keeping both the source and an export uses space; remove the original only after confirming you no longer need it.

Frequently Asked Questions

Can I speed up a video in iPhone Photos?
Photos offers speed-related editing for supported video types, particularly Slo-mo clips, but does not show the same speed controls for every ordinary video. Use iMovie when Photos does not provide the adjustment you need.

How do I make a normal iPhone video slow motion?
Add it to an iMovie project, select the clip, and use the speed control. The result may look less smooth than footage recorded in Slo-mo because ordinary video contains fewer frames for slow playback.

Can I speed up only part of a video?
Yes. In an editor such as iMovie, split the clip around the section you want to change, select that segment, and adjust its speed. Preview the transitions so the cut does not feel abrupt.

Can I watch an iPhone video at 2x speed?
That depends on the app playing the video. Some players provide a temporary playback-speed option; Photos may not offer a universal control for every video. Editing the clip creates a faster saved version instead.

Does slowing a video improve its detail?
No. A speed change alters timing, not the amount of detail captured. High-frame-rate recording can make slow motion smoother, but it cannot restore detail missing from the original footage.

Method: the standard formula for this calculation, rounded as each result states. See how the calculators work or report an error.