Convert a video to MP4, MOV or WebM
Choose the format you need and Vidmini converts your video on your own device. When the streams are already compatible, they are copied as-is: fast and lossless.
How it works
- 1
Choose or drop a video: MP4, MOV (including iPhone videos), M4V, WebM or MKV.
- 2
Pick the output: MP4 (H.264 + AAC), MOV (H.264 + AAC) or WebM (VP9 or VP8 + Opus).
- 3
Click Video Converter and download the result. Nothing was uploaded.
Containers and codecs: what a video format really is
A video file is a box holding several streams. The box is the container: MP4, MOV, WebM or MKV. The streams inside are compressed with a codec: H.264, HEVC, VP9 or AV1 for the picture, AAC, Opus or MP3 for the sound. The file extension only tells you the container, not how the content was encoded.
This is why two MP4 files can behave differently. An MP4 holding H.264 plays on almost any device, while an MP4 holding HEVC or AV1 may refuse to play on an older laptop or TV. When a video will not open, the fix is often to change the codec, not just the extension. Renaming a file from .mkv to .mp4 does not convert anything.
The three output choices
MP4 with H.264 video and AAC audio is the safe default. It plays on phones, computers, smart TVs, in every browser, in WhatsApp, Discord and social apps, and every video editor opens it. Choose it when you are unsure.
MOV with H.264 and AAC suits the Apple world: QuickTime, iMovie and Final Cut Pro, or a workflow that expects .mov files. The content is the same as the MP4 option, only the container differs.
WebM with VP9 (or VP8) video and Opus audio is made for the web. Use it to embed a video on a website or when a platform asks for WebM. It is an open, royalty-free format, but some Apple devices and older TVs handle it less well than MP4.
Copy when possible, re-encode when needed
Vidmini first checks what is inside your file. If the streams already use the codecs of the target format, they are copied into the new container without re-encoding. A MOV recorded in H.264 becomes an MP4 in seconds, with exactly the same quality. The tool shows “Lossless: no re-encoding” when this happens.
Otherwise the streams are re-encoded. A typical case is an iPhone video recorded in HEVC: converting it to MP4 with H.264 makes it play on Windows PCs, older Android phones and most TVs. Re-encoding uses the WebCodecs API and your device's hardware encoder when available. Note that HDR videos may look slightly faded after re-encoding, because tone-mapping is not supported yet.
Older formats and codec support
AVI, WMV and FLV files cannot be read by browsers, but they still work: they are first converted on your device by a built-in fallback, which is slower and downloads a 32 MB converter the first time. Decoding also depends on your browser: H.264, VP8, VP9 and AV1 are widely supported, and HEVC works on most recent devices. Chrome and Edge offer the widest codec support.
For a single, well-known conversion, the dedicated pages such as MOV to MP4 or MKV to MP4 explain the specifics of that format. After converting, Continue with this file sends the result to another tool, for example to compress it or make a GIF, without selecting the file again.
Frequently asked questions
Which format should I choose?
MP4 in almost every case: it plays everywhere. Choose MOV if an Apple app or a workflow requires .mov files, and WebM if you are publishing on a website or a platform that asks for it.
Does converting a video reduce its quality?
Not when the streams can be copied: the picture and sound are moved bit for bit into the new container. When a re-encode is needed, there is a small quality loss, usually hard to see. To make a file smaller on purpose, use the compressor instead.
Why is my conversion instant sometimes and slow other times?
An instant conversion means the codecs already matched the target and the streams were copied. A slower one means the video had to be re-encoded, for example from HEVC to H.264 or from H.264 to VP9 for WebM. Speed then depends on your device.
Can I convert AVI or WMV files?
Yes. MP4, MOV, M4V, WebM and MKV files are read directly by your browser. AVI, WMV and FLV files are first converted on your device by a built-in fallback, which is slower and downloads a 32 MB converter the first time; nothing is uploaded, and files up to 1 GB are accepted.
Is there a file size limit?
There is no limit set by us. The output is written to your browser's private storage, so desktop browsers handle files of several gigabytes. On phones the limit depends on free memory and storage.
Are my videos uploaded to a server?
No. The conversion runs entirely in your browser with WebCodecs and WebAssembly. The page only talks to vidmini.com to load its own code, uses no tracking cookies, and keeps working offline once loaded.