Change video speed
Faster or slower video in seconds, with every frame kept as it was.
Drop files here
or click to choose from your deviceAccepted: MP4, M4V, MOV
Up to 3 files per runUp to 150 MB per file5 runs per dayRemove limits with Pro✓ Works offline
Your files stay on your device
This tool runs entirely in your browser. Nothing is uploaded, nothing is stored, and you can even turn off your internet connection before you start.
Example
Example: a 3:20 dance routine slowed to 0.75× to learn the steps, music in key
A dance teacher filmed the recital routine on a phone: routine.mp4, 3 minutes 20 seconds at 30 frames a second, under the free plan’s 150 MB a file. Students want a slower copy to practise with. Settings: Speed 0.75×, Sound “At the new speed, same pitch”.
- Every frame is copied as it is, shown for 1 ÷ 0.75 times as long: 200 seconds ÷ 0.75 = 266.7 seconds, so the video lasts 4:27.
- The music is stretched to 4:27 without changing pitch, so the song stays in its key. With “pitch changed (like a tape)” it would be about 5 semitones lower.
- Press Change speed: the file is routine-0.75x.mp4, with the picture untouched and the sound saved as AAC.
| Speed | Length of the 3:20 video | Frames a second shown (filmed at 30) | Pitch “like a tape” |
|---|---|---|---|
| 0.25× | 13:20 | 7.5 | 2 octaves lower |
| 0.5× | 6:40 | 15 | 1 octave lower |
| 0.75× | 4:27 | 22.5 | about 5 semitones lower |
| 1.25× | 2:40 | 37.5 | about 4 semitones higher |
| 1.5× | 2:13 | 45 | 7 semitones higher |
| 2× | 1:40 | 60 | 1 octave higher |
| 3× | 1:07 | 90 | about 19 semitones higher |
| 4× | 0:50 | 120 | 2 octaves higher |
A 4:27 practice video where the steps come a quarter slower and the music still sounds like the song. 0.5× (6:40) is slower still for the hard bars, but at 15 frames a second the movement looks jerky; 0.75× stays fairly smooth.
How it works
- Drop an MP4 or MOV onto the box, from a phone, a camera or a screen recorder.
- Choose the speed: 2× plays twice as fast and lasts half as long; 0.5× is slow motion.
- Choose what happens to the sound: kept at its pitch, changed like a tape, or left out.
- Select Change speed and download the video.
Frequently asked questions
- Is the video re-encoded?
- No. Every frame is copied as it is and only the times they are shown at change, so the picture keeps all its quality and a phone clip is done in seconds. The sound is stretched to the new length and saved as AAC.
- Why is slow motion jerky?
- At 0.5× each frame is shown twice as long, so a 30-frames-a-second clip plays at 15. Smooth slow motion needs footage filmed at a high frame rate — a phone’s slow-motion mode at 120 or 240 fps slowed here to 0.25× plays smoothly.
- Does the voice sound higher when it is faster?
- Not unless you want it to. Keep pitch stretches the sound in time only (WSOLA, which pieces together short overlapping slices of the recording at the new pace), so voices keep their pitch and stay understandable. Change pitch plays it like a tape at another speed: faster and higher, or slower and lower.
- Can I slow down a dance or music video without the music going lower?
- Yes: keep Sound on “At the new speed, same pitch”. The music is stretched in time only, so it stays in its key at 0.75× or 0.5×. The tape-style option lowers it about 5 semitones at 0.75× and a full octave at 0.5×.
- Which videos does it take?
- MP4 and MOV files whose picture is H.264 or HEVC, which covers phones, most cameras and screen recorders. Another format is refused with a message saying so; convert it to MP4 first. Each file gets the speed added to its name, e.g. clip-2x.mp4.
- Is my video uploaded, and what are the free limits?
- Nothing is uploaded. The free plan allows 3 videos of up to 150 MB per run and 5 runs a day. Pro removes these limits. Chrome, Edge or Safari 16.4 or newer is needed for the sound.