Video Converter — free online tool
Does a player refuse to open your MKV, AVI or MOV file? Vidlora's converter turns it into MP4, the format played by virtually every device. Depending on the source codecs, it either simply changes the container or re-encodes the video, and it picks the right method on its own.
Drop a MP4, MOV, WEBM, MKV, AVI file here, or click to choose one
Processed temporarily, deleted afterDrop a MP4, MOV, WEBM, MKV, AVI file here, or click to choose one
MP4, MOV, WEBM, MKV, AVI
How it works
Container and codec: two separate concepts
A video file is a box (the container: MP4, MOV, MKV, AVI, WebM) holding streams compressed with a codec (H.264, HEVC, VP9, AAC, and so on). Converting can therefore mean two things: changing only the box, known as remuxing, which is fast and lossless, or re-encoding the streams with a different codec, which takes longer and involves a slight loss. The converter automatically determines the method needed based on your file and the target format.
Using it in a few steps
Upload your video, start the conversion and wait: remuxing takes only a few seconds, while re-encoding takes longer, in proportion to duration and resolution. The result is offered for download as soon as it is ready. You do not have to choose a codec or understand the technical options, which makes it a good first move when a file will not open on a given device.
When to convert to MP4
Action camera exports, screen recordings in MKV (common with OBS), old AVI files and MOV videos from a Mac are typical cases. MP4 is accepted by browsers, TVs, game consoles, smartphone editing apps and most sharing platforms. If your goal is a lightweight file, conversion alone is not enough: follow up with the video compressor.
Remuxing or re-encoding: what to expect
When the original codecs are already supported by MP4, for example H.264 with AAC audio inside an MKV, remuxing is almost instant and the quality is byte-for-byte identical. When they are not, for example with VP9 or unsupported audio, re-encoding is needed: the quality stays very close to the original but is no longer strictly identical, and the file size may change.
Device compatibility
An H.264 MP4 with AAC audio plays on virtually everything: iPhone, Android, Windows, macOS, TVs and browsers. Newer formats such as HEVC are less universal, notably in browsers. If a converted video does not play on a very old device, the cause is most often a profile or resolution that is too high rather than the container itself. In that case, resizing the video helps.
Tips and common problems
If the conversion fails, check that the file plays correctly on your own machine: a truncated file from an interrupted download will not convert. Subtitles embedded as separate tracks, found in some MKV files, are not guaranteed to survive in the final MP4. For specific formats, dedicated tools exist on Vidlora: MOV to MP4, WebM to MP4 or MP4 to WebM, with advice tailored to each case.
Limitations
Only MP4, MOV, WebM, MKV and AVI formats are accepted as input. The choice between remuxing and re-encoding is automatic, with no manual codec setting. Separate subtitle tracks and multiple audio tracks are not guaranteed to be kept in the final file.
Frequently asked questions
Does conversion lose quality?
Not when a simple remux is enough: the streams are copied as they are. If re-encoding is needed, the quality stays very close to the source but is no longer strictly identical.
What output format will I get?
An MP4 file, chosen for its compatibility with browsers, smartphones, TVs and editing software. To get WebM, use the dedicated MP4 to WebM tool.
Why are some conversions instant?
Because the codecs in your file are already compatible with MP4: only the container changes, without touching the picture or the sound. This is the case for many MKV files containing H.264.
My MKV file has several audio tracks, what happens to them?
The result is designed for simple playback and is not guaranteed to keep every track or separate subtitles. For multilingual use, check the resulting file before deleting the original.
Can I convert a video to AVI or MKV?
No, this tool's output is MP4. AVI, MKV, MOV and WebM are accepted as input only, which covers the vast majority of playback needs.
Does the file get smaller?
Not necessarily. Converting changes the format, not the file size target. To reduce the size, use the video compressor or the resizer afterwards.