How do I speed up or slow down a video online for free?

Choose a video, tap one of the eight speed buttons from 0.25× to 4×, and press Change speed. The video is re-timed and the audio is stretched to match with pitch correction, then exported as MP4. Nothing is uploaded — it all runs inside the browser tab.

Which speeds are available?

Eight fixed steps: 0.25×, 0.5× and 0.75× for slow motion, then 1.25×, 1.5×, 2×, 3× and 4× for fast forward. There is no custom value box and no 1× button, since leaving speed unchanged would do nothing. 2× is selected by default.

Does speeding up a video make voices sound like chipmunks?

No. Audio is time-stretched with FFmpeg’s atempo filter, which changes duration without shifting pitch, so narration stays natural at both 0.5× and 4×. Because atempo only handles a 0.5 to 2 range in one pass, extreme speeds are split into several chained stages automatically.

Will slow motion look smooth?

It will look smoother the higher the source frame rate. Slowing down re-times the frames you already have rather than inventing new ones, so a 30fps clip at 0.25× effectively shows each frame four times and can look stepped. Footage shot at 60fps or higher slows far more gracefully.

Does changing speed affect quality or file size?

Speed changes always re-encode, at H.264 CRF 21 with AAC audio, so there is one generation of compression. Size moves with duration: 2× roughly halves the length and the file, while 0.25× makes a clip four times longer and substantially larger. Plan for that before slowing a long recording.

What if my clip has no audio?

It is handled automatically. If the file has no audio track the encode is retried without the audio filter rather than failing, so silent screen recordings and exported animations work exactly the same way as clips with sound.

How long does it take?

Roughly real time against the output length, so a 2× speed-up of a ten-minute clip is quicker than a 0.5× slowdown of the same clip. Encoding runs on a single CPU thread with no GPU acceleration, and the engine is about 31MB to download the first time you use it.

What formats and file sizes are supported?

MP4, MOV, WebM, AVI and MKV up to 500MB, always exporting MP4 with H.264 and AAC so it plays everywhere. The download is named after your original with the speed appended, so a 2× export arrives as filename-2x.mp4.

Change Video Speed

Change video playback speed online free — speed up or slow down from 0.25× to 4× without audio pitch shift. Runs entirely in your browser — nothing uploaded.

Files never leave your deviceInstant — no upload waitFree, no sign-up

Choose a video or drag & drop it hereMP4, MOV, WebM… sped up or slowed down on your device, never uploaded

or import from

Change video speed from 0.25× slow motion to 4× fast forward, with the audio stretched to match and pitch kept natural rather than turning squeaky. Runs entirely in your browser using FFmpeg compiled to WebAssembly — no upload, no sign-up, no watermark, up to 500MB.

The eight speeds and what each is for

Effect on a 10-minute source clip.
Speed	New length	Typical use
0.25×	40 minutes	Analysing a golf swing, a trick shot, a technique
0.5×	20 minutes	Dramatic slow motion, dance or sport detail
0.75×	13m 20s	Subtle emphasis; following fast speech or instructions
1.25×	8 minutes	Tightening pacing without it being obvious
1.5×	6m 40s	Lectures and talking-head footage
2× (default)	5 minutes	Tutorials, walkthroughs, screen recordings
3×	3m 20s	Skipping repetitive steps in a demo
4×	2m 30s	Time-lapse feel from ordinary footage

These are fixed steps rather than a slider — there is no custom multiplier — and there is no 1× button because leaving the speed alone would just re-encode the file for nothing.

Why the audio does not go squeaky

Speed up a recording naively and you play the samples faster, which raises the pitch and makes everyone sound like a cartoon. That is not what happens here. The video timestamps are rescaled withsetpts while the audio goes through atempo, a time-stretching filter that changes duration and leaves pitch alone. Narration at 2× sounds like someone talking quickly, not like helium.

One implementation detail worth knowing, because it explains the extreme settings:atempo only handles a 0.5 to 2 range in a single pass. Anything beyond that is automatically split into chained stages — 4× runs as two 2× passes, 0.25× as two halvings. Quality holds up well, though pushing to the outer settings on music or heavy reverb is where stretching artefacts become audible.

Slow motion depends on your source frame rate

This is the expectation to set correctly. Slowing a video re-times the frames that already exist; it does not generate new ones. A 30fps clip played at 0.25× has to hold each frame four times as long, which reads as stepped or stuttery motion. The same setting on 60fps or 120fps footage looks smooth, because there were more frames to spread out in the first place.

So if smooth slow motion matters, capture at a high frame rate to begin with — a phone's 120fps or 240fps mode exists exactly for this. No amount of processing recovers motion that was never recorded.

File size moves with duration, in both directions

Easy to forget when slowing something down. Because the output is re-encoded at a constant quality level rather than a fixed size, a longer video is a bigger file. Speeding up shrinks things pleasantly: 2× roughly halves both length and size. Slowing down does the reverse, and 0.25× on an already large clip can produce something awkward to share. Run it through thevideo compressor afterwards if that happens.

How this compares to the alternatives

Re-timing one clip, three ways.
	ToolJiffy	Typical online tool	Desktop editor
Video uploaded to a server	No	Yes	No
Sign-up	No	Often to export	Install or licence
Pitch-corrected audio	Yes, at every speed	Varies; often not	Yes
File-size limit	500MB	Commonly capped free	None practical
Watermark	Never	Common on free tiers	No
Custom speed value	No — eight presets	Sometimes	Yes
Price	Free, unlimited	Free tier then paid	Free to paid

Frequently Asked Questions

How do I speed up or slow down a video online for free?
Choose a video, tap one of the eight speed buttons from 0.25× to 4×, and press Change speed. The video is re-timed and the audio is stretched to match with pitch correction, then exported as MP4. Nothing is uploaded — it all runs inside the browser tab.
Which speeds are available?
Eight fixed steps: 0.25×, 0.5× and 0.75× for slow motion, then 1.25×, 1.5×, 2×, 3× and 4× for fast forward. There is no custom value box and no 1× button, since leaving speed unchanged would do nothing. 2× is selected by default.
Does speeding up a video make voices sound like chipmunks?
No. Audio is time-stretched with FFmpeg’s atempo filter, which changes duration without shifting pitch, so narration stays natural at both 0.5× and 4×. Because atempo only handles a 0.5 to 2 range in one pass, extreme speeds are split into several chained stages automatically.
Will slow motion look smooth?
It will look smoother the higher the source frame rate. Slowing down re-times the frames you already have rather than inventing new ones, so a 30fps clip at 0.25× effectively shows each frame four times and can look stepped. Footage shot at 60fps or higher slows far more gracefully.
Does changing speed affect quality or file size?
Speed changes always re-encode, at H.264 CRF 21 with AAC audio, so there is one generation of compression. Size moves with duration: 2× roughly halves the length and the file, while 0.25× makes a clip four times longer and substantially larger. Plan for that before slowing a long recording.
What if my clip has no audio?
It is handled automatically. If the file has no audio track the encode is retried without the audio filter rather than failing, so silent screen recordings and exported animations work exactly the same way as clips with sound.
How long does it take?
Roughly real time against the output length, so a 2× speed-up of a ten-minute clip is quicker than a 0.5× slowdown of the same clip. Encoding runs on a single CPU thread with no GPU acceleration, and the engine is about 31MB to download the first time you use it.
What formats and file sizes are supported?
MP4, MOV, WebM, AVI and MKV up to 500MB, always exporting MP4 with H.264 and AAC so it plays everywhere. The download is named after your original with the speed appended, so a 2× export arrives as filename-2x.mp4.