Changing a video's speed is one of the simplest edits, and one of the most useful. Speed a clip up and a long process becomes a time-lapse; slow it down and a splash, a jump or a product reveal turns into slow motion. You can do it for free in a browser, without installing an app or creating an account. This guide covers the speed factors that work well, what happens to the sound, why slow motion sometimes looks choppy, and how the options on phones and computers compare.
Speed up or slow down a video online
The change video speed tool runs in your browser. It does not need an account or credits, it adds no watermark, and your video is processed on your device instead of being uploaded.
- Open Change video speed and upload an MP4, MOV or WebM file of up to 5 minutes and 300MB.
- Set Speed to any value from 0.25 to 4. Typing a number works, and the arrows move in steps of 0.25. Below 1 is slow motion, above 1 is faster, and 1 keeps the original timing.
- Click Change speed and wait while the clip is processed.
- Preview the result, then click Download speed edit to save an MP4.
The whole clip changes by the same factor. The tool has no speed ramps and no way to change only part of a clip, so cut out the section you need first if you only want to speed up or slow down one moment. Files above 100MB or 60 seconds can be slow to process, and phones with limited memory may struggle with long or high-resolution clips.
Common speed factors
The new length is the original length divided by the speed. For a 10-second clip:
| Speed | 10-second clip becomes | What it is good for |
|---|---|---|
| 0.25x | 40 seconds | Extreme slow motion; needs very smooth source footage |
| 0.5x | 20 seconds | Classic slow motion, calm backgrounds |
| 0.75x | About 13.3 seconds | A gentle slow-down that still looks natural |
| 1.25x | 8 seconds | Tightening a demo or walkthrough |
| 1.5x | About 6.7 seconds | Faster tutorials and talking clips |
| 2x | 5 seconds | Fast forward |
| 4x | 2.5 seconds | Time-lapse style, the fastest the tool goes |
Need more than 4x? Download the result, upload it again and apply a second pass: 4x twice is 16x. Each pass re-encodes the video, so keep the number of passes low. Going slower than 0.25x is not worth a second pass: it only stretches the same frames further, so the result gets choppier.
Speed up a video for a time-lapse
A time-lapse is mainly a fast-forwarded clip of something slow: clouds crossing the sky, a drawing taking shape, a room being set up, traffic at dusk. Some tips:
- Film something that changes slowly. A fast-forwarded conversation just looks frantic. Slow, steady change reads as a time-lapse.
- Keep the camera still. A tripod or a phone propped against something makes the result look intentional. Speeding up shaky footage makes the shake worse.
- Choose the speed by the length you want. To fit a 3-minute process into 45 seconds, divide: 180 / 45 = 4, so use 4x.
- Expect the sound to change. At 4x, speech is a hurried blur. Most time-lapses are better with the sound muted or replaced with music.
Slow down a video for slow motion
Slowing a clip down stretches the frames you already have. Nothing is added in between, so how smooth the result looks depends on how the footage was filmed.
A rough rule: the footage needs about playback frame rate divided by speed frames per second. For a 30 FPS video to look smooth at 0.5x, it needs to have been filmed at around 60 FPS. At 0.25x, it needs around 120 FPS. Footage filmed at 24 or 30 FPS shows each frame for longer when slowed, and fast motion starts to look stuttery.
What to do about it:
- Film in your phone's slow-motion mode if you know you will slow the clip down. Phone cameras usually record these clips at a much higher frame rate, often 120 or 240 FPS depending on the model and settings.
- Pick a gentler speed. 0.75x or 0.5x usually looks fine on ordinary footage, while 0.25x is best kept for footage with a high frame rate.
- Choose subjects that move smoothly, such as flowing water, hair, fabric, smoke or a camera glide, instead of fast, jerky action.
- Try frame interpolation if you need it. Some editors and ffmpeg can generate in-between frames. It can look smoother, but it can also introduce visible artifacts, and LoopVideo's tool does not do it.
What happens to the sound
Sound is processed together with the picture. When you speed a clip up the audio plays faster, and when you slow it down the audio stretches. The tool changes the audio's tempo while keeping the pitch roughly the same, so voices do not turn into chipmunks or growls. If the clip has no audio track, or the audio cannot be processed, the result is exported without sound.
Speech is the weak spot. Voices are easy to follow at 1.25x to 1.5x, but at 2x and above they get hard to understand, and slowed speech sounds drawn out and unnatural. If you want a silent result or a different soundtrack, mute or replace the audio in an editor after changing the speed. The tool has no mute option of its own.
Speed up or slow down a video on a phone or computer
LoopVideo's tool works in mobile and desktop browsers, but you can also use what is already on your device. Menu names change between app versions, so treat the paths below as a starting point.
| Where | How | Good to know |
|---|---|---|
| iPhone Photos | For clips filmed in Slo-mo mode, tap Edit and move the slow-motion section markers on the timeline. | It only adjusts where slow motion starts and stops in Slo-mo clips; it doesn't change other videos. |
| iMovie | Select a clip in the timeline and use the speed control to make it slower or faster. | Free on Apple devices. Check which speed range your version offers. |
| CapCut | Select a clip and open its speed options. There is a constant speed setting and a speed-curve option for ramps. | Good for changing speed within a clip. Layout varies by version and platform. |
| Premiere Pro | Right-click a clip and choose Speed/Duration, or press Cmd/Ctrl+R. | Desktop editor with a subscription. |
| Instagram and TikTok | Both apps have speed controls in their camera and editing tools. | Options and menu names change often. Check the app before relying on a particular range. |
| ffmpeg | Free command-line tool. Doubling the speed: ffmpeg -i in.mp4 -filter_complex "[0:v]setpts=0.5*PTS[v];[0:a]atempo=2[a]" -map "[v]" -map "[a]" out.mp4 | Use setpts=2*PTS and atempo=0.5 for half speed. Older versions limit atempo to 0.5 to 2. |
Media players such as VLC and YouTube can play a video faster or slower while you watch, but that does not save a new file. For a video you will post or send, you need to export the changed speed using one of the options above.
Speed edits for Reels, Stories and TikTok
A few uses where speed changes are common:
- Slow motion for a reveal. A product turning, a pour or a jump looks better at 0.5x. Trim to the moment that matters first, because slow motion makes a clip longer.
- Fast-forward to fit a time limit. Speeding a long clip up is a quick way to keep it within a short-video slot without cutting content. For platform limits, check the app, since they change; our guide to looping a video on Instagram explains how Stories and Reels handle length.
- Match the beat. If the video goes with music, try 1.25x or 1.5x to tighten slow footage, or 0.75x to stretch the footage across a longer sound.
- Reframe for vertical. If the clip is not already 9:16, crop the video before or after changing the speed.
Make the sped-up or slowed clip loop
Short speed edits are often meant to repeat as a background, in a Story or on a website. Once the timing feels right, open the LoopVideo workspace and choose the AI seamless loop. It generates a transition of about five seconds from the last frame back to the first, then exports one cycle. AI requires sign-in, and email accounts must be verified. The one-time free trial adds a visible watermark, and one paid credit produces a watermark-free result. The free repeat preview in the same workspace needs no account.
If you only need more running time, slowing a clip down is one option among several; how to make a video longer compares them. To play a clip backwards, see how to reverse a video.
FAQ
How do I speed up a video for free?
Upload it to the change video speed tool, set a speed above 1x up to 4x, click Change speed and download the MP4. It is free, needs no account and adds no watermark.
How do I slow down a video online?
Use the same tool and set a speed below 1x. At 0.5x the clip lasts twice as long, and at 0.25x, the slowest setting, four times as long.
Does changing the speed change the sound?
Yes. The audio speeds up or slows down with the picture. The tool keeps the pitch roughly the same, so voices do not turn high or deep. If the clip has no sound track or the audio cannot be processed, the MP4 has no sound.
Why does my slow-motion video look choppy?
Slowing a clip down stretches the existing frames instead of creating new ones. Footage filmed at 24 or 30 FPS looks stuttery at 0.5x and below. Film in your phone's slow-motion mode, use a gentler speed, or try a tool with frame interpolation.
Can I change the speed of only part of a video?
Not in LoopVideo. The whole clip changes by the same factor. Cut the part you need in a video editor first, or use an editor with speed ramps, such as CapCut or Premiere Pro.
What is the maximum and minimum speed?
From 0.25x to 4x. Values outside that range are limited to it. To go faster than 4x, process the result a second time.
Is my video uploaded?
No. The speed tool processes the video in your browser on your device.
Which formats and sizes work?
MP4, MOV and WebM files of up to 5 minutes and 300MB. The result downloads as an MP4.
