Convert Video to MP4 or WebM
Convert supported video files to MP4 or WebM in your browser. Try compatible stream copying or re-encode, with optional audio retention.
- 01Add your video
- 02Adjust & preview
- 03Export your result
Video workspace
Private local processing with FFmpeg WebAssembly. First export downloads the processing engine; no video uploads.
Browser playback support varies by codec. FFmpeg may accept files the preview cannot play.
Export settings
Choose a video to begin.
FFmpeg diagnostics
Logs appear here during export.
When to use this tool
Create an MP4 for a compatible player or a WebM copy for a supported web workflow. Select the output based on where the file will play, then test it on the destination device.
How to use Convert Video to MP4 or WebM
- Choose a source video and check whether the browser can preview it.
- Select MP4 or WebM, choose the available quality and audio settings, and optionally try fast stream copying.
- Convert and download the result, then verify picture, duration and audio in a compatible player.
Supported video formats and output
Accepts MP4, MOV, WebM, MKV, AVI and M4V when their codecs are supported by the bundled FFmpeg build. Export formats are MP4 and WebM. MP4 re-encoding uses H.264/AAC; WebM re-encoding uses VP8/Opus at a 640-pixel width with proportional height; this can enlarge smaller sources.
Choose format conversion or compatible stream copying
| Need | Useful choice | Check afterward |
|---|---|---|
| A newly encoded H.264/AAC copy | MP4 with fast copying off | Picture, retained audio and playback in the receiving application. |
| Keep compatible streams without re-encoding | Try fast copy for an eligible MP4/M4V or WebM source | Copying retains codecs; it does not turn every input into a more compatible codec. |
| A WebM web-workflow copy | WebM encoding | Fixed VP8/Opus preset and 640-pixel width; smaller sources can be enlarged. |
- Keep the original and choose the format required by the recipient. Use the available audio option deliberately.
- If a specific codec is required, turn fast copying off rather than inferring codecs from the output extension. A failed eligible copy attempt can fall back to encoding.
- For WebM, use an input within the 90 MiB limit. That restriction also applies before an eligible WebM copy attempt. The MP4 quality menu does not change the fixed WebM encoding preset.
- Inspect the downloaded file in the target player. A successful browser source preview is not a destination-compatibility check.
Authored decision workflow, not a new converted-file demonstration. No AVI/MOV output or universal playback guarantee is implied. Use Compress Video when resolution and compression controls are the main task.
Limits and quality
The general staging limit is 450 MiB; WebM export rejects inputs above 90 MiB. Compatible stream copying can retain original codecs and dimensions. WebM re-encoding uses a fixed memory-saving preset; MP4 quality choices do not control its bitrate. Output size can increase.
Local processing and engine downloads
The application processes selected media in this browser. The FFmpeg engine and workers load from a third-party CDN when first needed; those requests disclose ordinary connection information. Keep the original files and check your downloaded result. Export needs JavaScript, WebAssembly and worker support.
Frequently asked questions
Can this export AVI or MOV?
No. Those containers may be accepted as inputs, but the current output choices are MP4 and WebM.
Does fast copy change the codec?
No. It copies compatible streams without re-encoding. When copying is unavailable or fails, conversion may fall back to encoding.
Related workflows
Choose a file for a receiving application
Select the destination format rather than simply changing the filename. Convert a compatible source, then inspect picture, duration and sound in the receiving player.
Before choosing the output
Fast copy retains compatible codecs instead of changing them. MP4 and WebM have different encoding settings and limits; output size can increase.
Read the format and processing details above. Keep the original and inspect the downloaded result.