Video & audio converter
MP4 Converter
Convert WEBM, MKV, AVI, MOV or M4V videos to MP4 with H.264 video and AAC sound, the format almost every device plays. Free, no sign-up.
Tested by Thiago · Updated
Free, no sign-up · Sent over HTTPS · Files are deleted from our server automatically after 30 minutes
How to convert video to MP4
- Add your files: drag them into the box above, or click "Choose files".
- Click "Convert to MP4" and wait a few seconds while we process them.
- Download your MP4 files. Uploaded files are deleted right away, and converted files are removed from our server after 30 minutes.
Why convert videos to MP4?
MP4 is the one video format that works everywhere: phones, TVs, browsers, editing apps and every social network. This MP4 converter takes WEBM, MKV, AVI, MOV and M4V files, which are common from screen recorders, older cameras and downloads of your own content, and turns them into MP4 with H.264 video and AAC audio.
- Your screen recording (WEBM or MKV) needs to be shared or edited in an app that only accepts MP4.
- An old AVI video will not play on your phone or TV.
- A platform you upload to asks for MP4 files.
- You recorded a video call or a class in your browser and the recording was saved as WEBM.
What happens to each format
- WEBM, usually from a browser-based screen recorder or a web app: the video and the Opus or Vorbis sound are rebuilt as H.264 and AAC. Our 20-second screen-recording test went from 4.4 MB as WEBM to 2.0 MB as MP4.
- MKV: only one audio track and no subtitles make it into the MP4. If the file has two languages, check that the MP4 plays the one you want before deleting the MKV.
- AVI from old cameras and phones: odd picture sizes are reduced by one pixel to even numbers, which this H.264 format requires. A 641 by 481 test file came out at 640 by 480, and 6.9 MB of old-style video became a 0.9 MB MP4.
- M4V: already close to MP4, but it is re-encoded too, so you get the same predictable H.264 and AAC result as with every other format.
Ready for websites and online courses
Besides the common codecs, the MP4 is saved with its index at the start of the file. A browser can then start playing it while it is still downloading, instead of waiting for the whole file. That matters if you place the video on your own site, in a shop or on a learning platform that streams the file as it is.
The conversion always goes in one direction. This page only creates MP4 files; it cannot turn an MP4 into WEBM, MKV, AVI or MOV.
Tips for the best result
- The output is H.264 video with AAC audio at high quality, the most compatible combination.
- Already have an MP4 that is too big? Use the video compressor instead.
- Converting long videos can take a few minutes; you can watch the progress and time left.
About these formats
Video formats: We accept MP4, M4V, MOV, WEBM, MKV and AVI videos, the formats used by phones, cameras, screen recorders and most editing apps.
MP4: The most widely supported video format. It plays on phones, browsers, TVs and social networks, with good quality at a reasonable size.
Frequently asked questions
Which formats can I convert to MP4?
WEBM, MKV, AVI, MOV and M4V.
Why is MP4 the most compatible format?
MP4 with H.264 video and AAC audio is supported by virtually every device, browser and app made in the last decade.
Is there a file size limit?
Up to 200 MB per file, and up to 20 files per batch.
My MKV has two audio languages. Which one is kept?
One audio track is kept: the one marked as the default track in the file, which is usually the first. If no track is marked, the one with the most channels wins, for example 5.1 over stereo. If you need another language, the MKV has to be edited first in a video tool that can choose tracks.
Are subtitles inside the MKV kept?
No. Subtitle tracks are not copied into the MP4. Keep the original MKV, or a separate subtitle file, if you need them.