How to Slow Down a Video on iPhone

Choose the right starting point

A clip recorded for slow motion and a regular video played more slowly are different starting materials. High-frame-rate capture can provide more distinct frames for slower playback. A normal recording still works for showing a short action carefully, but its limits become more visible when you stretch it substantially.

Keep the original in your library or project folder. If the action matters—for example, the sequence of events in a demonstration—retain an unaltered copy alongside the edited version so the speed change does not become misleading.

Make a short slow-motion copy

1. Open the original and identify the exact action to slow down.
2. For a supported Slo-mo clip, use Photos’ editing controls to adjust the slow portion.
3. For a regular clip, import it into an editor with a playback-speed control.
4. Start with a modest reduction, such as 0.5×, and preview the motion.
5. Check how the app treats sound; mute, preserve, or replace it only as intended.
6. Export a new copy and replay it from the saved location.

Video Speed: Slow Motion is an SFByte option whose listing describes speed changes. Confirm the controls, supported imports, and purchase requirements in the version you install. Do not assume every editor uses the same slider or preserves pitch in the same way.

Work out the new duration

For a whole clip at one constant speed, new duration equals original duration divided by the speed multiplier. A twelve-second clip at 0.5× becomes approximately twenty-four seconds. At 0.25×, the same clip becomes forty-eight seconds.

This simple calculation does not apply to an entire project with several different speed segments unless you calculate each segment separately and add the results. Transitions and intentional freezes can also change the final timeline. Check the duration of the exported file rather than relying only on a rough estimate.

Why slower footage can look choppy

An editor has to display the available frames for longer or construct intermediate frames. Repeated frames can look like stepping. Interpolated frames may appear smoother but can create distortions around fast motion, thin objects, or overlapping subjects. These approaches do not recover moments the camera never captured.

For a future recording, plan the capture settings around the intended effect and available light. Higher frame rates have practical tradeoffs, including storage and lighting needs. 30 FPS versus 60 FPS explains the recording decision; it is separate from simply choosing a slower playback rate afterward.

Sound needs its own review

Listen to speech, background music, and important sound cues after changing speed. Depending on the editor, slowed sound may have a different pitch, be stretched with pitch correction, or be muted. A demonstration might work better with a separate explanation recorded at normal speed, but only use audio you have permission to include.

Do not judge the final soundtrack solely in the editing preview. Play the exported file and check that its sound begins and ends where you expect. If the soundtrack disappears, follow the silent-export checks before recreating the project.

File size and sharing

A longer output can be larger at the same bitrate. Use the Video Size Calculator with the new duration, then check the actual result. If sharing requires a smaller copy, compress that copy after you are satisfied with the motion and retain the higher-quality original.

Can I slow only one moment?

Use a supported slow-motion range or split the timeline and change only the relevant segment. Check the transitions between normal and slow playback so the result is understandable.

Will renaming the file make it slow motion?

No. Speed must be represented by an edit, playback metadata the destination understands, or a rendered export. A new filename alone does not change timing.