You can slow down a video either by changing the playback speed for yourself (no file editing), or by editing the file so it permanently plays in slow motion.

Basic idea

Slowing a video means:

  • Reducing its playback speed (for example from 1x to 0.5x), so the same frames take longer to play.
  • Optionally keeping or adjusting the audio so it still sounds natural, or muting it if the slowed sound is distracting.

Quick ways on popular platforms

These methods only change what you see; they do not edit the original file.

  • YouTube (web or app)
    • Tap/click the gear icon.
    • Choose “Playback speed” and pick 0.75x, 0.5x, or 0.25x to slow it down.
  • Social apps that lack built‑in slow‑mo (many Instagram videos, etc.)
    • Screen‑record the clip on your phone.
    • Open it in your Photos or gallery app and use the speed/slow‑motion editing tool to reduce speed.

These are great if you just want to understand a tutorial better or catch details in a fast clip.

Online tools to slow a video file

These services let you upload a file, choose a slower speed, and download a new slow‑motion version.

  • Simple slider‑based tools
    • Sites like Adobe Express, Canva, VEED, and similar editors let you:
      • Upload your video.
      • Move a speed slider or select a speed like 0.5x or 0.25x.
      • Apply the change and download the slowed file.
  • More control over sections
    • Some tools (for example ezgif’s video speed editor) let you:
      • Type an exact factor (e.g., 0.5 for half speed).
      • Select start/end times so only part of the video is slowed.
      • Decide whether audio stays normal, slows with video, or is muted.

Online tools are useful if you do not want to install software and your clip is not huge.

Editing apps and desktop editors

If you make content regularly or want more precise control, editing apps give you better options.

On a phone

Many mobile editors (and some gallery/Photos apps) let you:

  • Import a video into a timeline.
  • Tap the clip and change a speed value from 1x down to 0.5x or 0.25x.
  • Optionally apply slow motion only to certain portions by splitting the clip and changing speed on just those segments.

This is enough for simple sports slow‑mo, tutorials, or dramatic moments in short videos.

On a computer

Standard video editors work in a similar way:

  • Place the clip on the timeline.
  • Use a speed or time‑stretch control to reduce speed, e.g. to 50% (half speed), which makes the clip longer.
  • For smoother results, record or use footage with a higher frame rate (for example 60 fps) so slowing it introduces less choppiness.

Editors also let you add music, titles, and cuts around the slow‑motion sections for a more polished result.

Tips for better slow motion

  • Use higher frame rate when possible
    • Footage shot at 60 fps or higher stays smoother when slowed, compared with 24–30 fps clips.
  • Choose how audio behaves
    • Slowed speech can sound distorted, so consider:
      • Muting original audio and adding music.
      • Keeping only key sounds (like a ball hitting a racket) and lowering everything else.
  • Don’t over‑slow
    • Slight slow‑downs (like 0.75x or 0.5x) often look more natural than extreme ones, unless you are going for a very stylized effect.

TL;DR:
To slow down a video, either change playback speed in the player (easiest for quick viewing) or use an editor/online tool that lets you set a speed below 1x and export a new file, ideally using high‑frame‑rate footage for smoother slow motion.

Information gathered from public forums or data available on the internet and portrayed here.