Choose a video
Select a video and let the browser detect its duration.
Change Video Speed Online
Speed up or slow down video and audio together. Compare the expected duration before creating a synchronized MP4.
Local video tool
Choose a video to retime
Choose a video
or drag and drop
MP4, MOV, or WebM · up to 250 MB
How it works
Select speed
Choose 0.5×, 0.75×, 1×, 1.25×, 1.5×, or 2× and review the expected duration.
Download MP4
Video timestamps and audio tempo are adjusted together to remain synchronized.
Synchronized video and audio speed
Video timestamps use FFmpeg's setpts filter while audio uses atempo. The offered 0.5×–2× range stays inside the reliable single-filter audio range.
A 2× result is approximately half the original duration, while 0.5× is approximately twice as long. Re-encoding is required for both tracks.
Frequently asked questions
Will the audio stay synchronized?
Yes. Video timestamps and audio tempo use the same selected speed factor.
Can I make a video twice as fast?
Yes. Choose 2×; the expected duration will be about half the original.
Can I create slow motion?
Choose 0.5× or 0.75×. This repeats timing rather than generating new motion-interpolated frames.
Is processing private?
Yes. The video is retimed locally and is never uploaded.