Format Converter
Convert video between MP4, WebM and MOV and keep the quality
Your files are processed on your device. The first use downloads a processing engine, which your browser then keeps.
Drop a video to convertTap to choose a video to convert
or click to browseor tap to choose
Works with MP4, MOV, MKV, AVI, WebM, WMV, FLV, 3GP and similar video files. Output: MP4, MP4 for web, WebM or MOV.
Large files (over 5 GB) may take longer or run out of browser memory
About Format Converter
Converts a video between MP4, web-optimized MP4 (fast-start for HTML5), WebM, and MOV. Prefer “MP4 for web” for sites; use WebM only when you specifically need a .webm file. Runs entirely in your browser — the video never leaves your device.
Upload your video, choose the format you want to convert it to, and download the converted file once processing finishes.
For websites and embeds, choose “MP4 for web” (fast-start). WebM works in modern browsers but is slower to encode in-browser; use a short clip if it feels stuck. Because WebM is always re-encoded, short clips often come out larger than the original.
Watch: Format Converter in Action
- Which video format should I use if I'm not sure what's expected?
- MP4 is the safest default — it has the widest compatibility across devices and platforms of any common video format.
- Why does converting take a while for a large file?
- Converting between formats generally re-encodes the entire video, not just relabels the file, so larger files or longer videos take noticeably longer to process.
- What is the difference between MP4 and MP4 for web?
- In this tool they produce the same kind of file: both are written with the fast-start setting, which puts the playback index at the start so it can begin before fully downloading. The labels differ, but the settings used are the same either way.
- Why did my conversion take only seconds?
- When a video is already H.264 with AAC audio and you choose MP4 or MOV, the streams are copied into the new container without re-encoding. That is quick and loses no quality. The summary line says the video was copied into the new format.
- What are the settings for re-encoded MP4 and WebM?
- MP4 and MOV re-encodes use H.264 at CRF 23 with the veryfast preset and AAC audio at 128 kbps. WebM uses VP8 at 1 Mbps with Vorbis audio at 96 kbps and limits the width to 1280 pixels.
- Why is the converted file bigger than the original?
- A re-encode can raise size, notably when going from WebM to H.264 MP4, which the tool notes in its summary. Repackaging does not grow a file. For a smaller result, run the output through the Compress Video tool.
- How do I convert MOV to MP4?
- Drop the MOV file, leave the output on MP4 and press Convert. When the picture is H.264 and the sound is AAC, the streams are copied into an MP4 in seconds with no quality loss. Other codecs, such as the HEVC many phones record, are re-encoded, which takes longer.
- Which MP4 should I pick for a website?
- Either. In this tool MP4 and MP4 for web write the same fast-start file, with the playback index at the front so a page can start playing before the whole file downloads. Use WebM only when you specifically need a .webm file.
- Is my video uploaded?
- No. The conversion runs in your browser, so the video is not sent to a server. The video engine, about 25 MB, is downloaded once before your first conversion.
- Can I convert audio-only files or formats like MKV and AVI?
- The picker accepts files that look like video, including common extensions beyond MP4, and anything the engine can read can be converted to the four outputs. Audio-only files are rejected here; use the Audio Converter for those.
How to use Format Converter
Drop a video; the tool rejects files that do not look like video. Open Output Format and choose MP4 (widely compatible), MP4 for web (streaming / HTML5), WebM (HTML5 web video) or MOV (Apple / QuickTime), then press Convert.
For MP4 and MOV targets, the tool first looks at what is inside the file. If the picture is H.264 and the sound is AAC, or there is no sound, it only repackages the streams into the new container, which takes seconds and does not touch quality. Otherwise it re-encodes with H.264 and AAC. After finishing, a line states the old and new size and whether the video was copied or re-encoded. Preview, then download; a file already ending in the chosen extension gets _converted added.
When to use it
Use it when a site or editor rejects your video's container, when a screen recording in MOV or MKV needs to become MP4 for sharing, or when you want a WebM version for a web page. Repackaging between MP4 and MOV is especially handy because, for compatible files, it is fast and lossless.
When not to use it
It does not shrink a video on purpose or change resolution, apart from the WebM width cap, so for a smaller file use the Compress Video tool. Conversion to WebM is slow in a browser, so do not pick it for a long recording. For batch work on many files or professional codecs such as ProRes, a desktop converter fits better.
Tips for best results
If your source is already H.264, choosing MP4 or MOV is nearly instant and keeps the exact quality, so prefer those when the goal is only compatibility. WebM is encoded at a fixed 1 Mbps and capped at 1280 pixels wide, so it suits short clips. If a conversion looks stuck, test with a short clip first to separate a slow job from a real fault.
Limitations
Output options are limited to the four formats in the menu, with no controls for quality, resolution or frame rate. WebM uses VP8 and Vorbis at a fixed bitrate and is scaled down when wider than 1280 pixels. Anything not already H.264 with AAC is fully re-encoded at one fixed quality setting. Very large videos must fit in browser memory and may fail on phones.
Privacy
The video is converted by an engine running in your own browser, so the file is not uploaded and no server sees it. The engine, about 25 MB, is fetched once from a public CDN before the first conversion. Large videos are held in your device's memory during the job, and the result is saved straight from the page, not from any server copy.
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