Change Video Speed
Speed up or slow down any video clip smoothly while syncing audio automatically. Free, private, no uploads required — it all works in your browser.
Everything runs inside your browser — your file is never uploaded to a server.
First run downloads the media engine (~30 MB) once, then it stays cached.
About this tool
This tool changes the playback speed of a video, from ultra slow motion to fast time-lapse style playback, while automatically adjusting the audio pitch so it doesn't sound like a chipmunk or a growl. Processing happens entirely with FFmpeg compiled to WebAssembly running inside your browser tab, so nothing is uploaded anywhere. You pick a speed multiplier such as 0.5x for half speed or 2x for double speed, and the tool re-encodes both the video frames and the audio track to stay in sync at the new duration. It's handy for creators who want a dramatic slow-motion reveal, for turning a long screen recording into a punchy fast-forward tutorial, or for matching a clip's length to a specific music track. Because everything runs locally, even large 4K clips process without waiting in an upload queue or worrying about file size limits imposed by cloud services.
How to use this tool
1. Upload your video
Drag and drop the clip whose speed you want to change.
2. Choose a speed multiplier
Pick a preset like 0.5x or 2x, or enter a custom speed value.
3. Process the clip
The tool adjusts video and audio together locally in your browser.
4. Download the result
Save your sped-up or slowed-down video to your device.
Why use this tool
Manually retiming a video while keeping audio pitch correct usually requires a full non-linear editor with time-remapping tools. This browser-based tool does the same job in one click, without installing software, creating an account, or worrying about upload limits, making it a fast option for social media edits, sports analysis clips, or tutorial pacing adjustments.
Tips & best practices
- Use 0.5x speed for slow-motion highlights of sports or action footage recorded at a normal frame rate.
- Speed up long screen recordings to 1.5x or 2x to create punchier software tutorials.
- Test a short section first at extreme speeds to check the audio still sounds natural before processing the full clip.
Common use cases
- Creating dramatic slow-motion replays from action or sports footage.
- Turning a long tutorial screen recording into a faster paced video.
- Matching video length to a specific song for a music video edit.
- Producing quick time-lapse style clips from regular speed recordings.
- Slowing down a dance or workout video for step-by-step analysis.
Frequently asked questions
Will the audio still match the video after changing speed?
Yes, the audio pitch and duration are automatically adjusted to remain synchronized with the new video speed, whether you speed up or slow down the clip.
How much can I slow down or speed up a video?
Typical useful ranges are 0.25x to 4x. Extreme values beyond that can look choppy or unnaturally fast depending on the original frame rate.
Does changing speed affect video resolution or quality?
No, resolution stays the same. Only playback speed and duration change, though re-encoding may apply a small amount of standard video compression.
Can I speed up only the audio without changing the video?
This tool changes both together to keep them in sync. For audio-only speed changes, use a dedicated audio speed tool instead.
Is there a file size limit for changing video speed?
There's no artificial limit since processing happens on your device, though very large files will naturally take longer depending on your computer's power.
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