MKV to MP4 Converter
Convert MKV to MP4 online for free: nothing to install, no watermark, files encrypted in transit and deleted automatically after conversion.
Advanced options
Drag & drop your MKV file here, or
How to convert MKV to MP4 in 3 steps
- 1
Upload your MKV file
Drag and drop or select the MKV file you want to convert.
- 2
Choose MP4 as output
The output format is pre-selected for you — just confirm and start the conversion.
- 3
Download your file
Once processing finishes, download your converted MP4 file instantly.
Converting MKV to MP4: what to know
When you need it
MKV is common for films, series and recordings from capture software, but many TVs, phones, video editors and social networks only accept MP4. Converting makes the video play on those devices and upload to those sites.
What to expect
When the MKV holds codecs MP4 supports, which is the usual case (H.264 or H.265 video with AAC, MP3 or AC-3 audio), the streams are copied into the new container without re-encoding: it takes seconds and loses no quality. Otherwise the video is re-encoded, which takes longer. Subtitle tracks are generally not carried over, so keep the MKV if you need them.
Tip: Choosing a resolution under Advanced options forces a full re-encode. Leave it on the original to get the fast, lossless copy whenever it is possible.
MKV vs MP4: what is the difference?
| MKV | MP4 | |
|---|---|---|
| Full name | Matroska Video | MPEG-4 Part 14 |
| Type | Video container | Video container |
| Compression | Depends on the codec | Depends on the codec |
| Developed by | Matroska.org | MPEG (ISO/IEC) |
| File extension | .mkv | .mp4 |
What is MKV?
MKV (Matroska) is an open, royalty-free container that can hold any number of video, audio and subtitle tracks plus chapters in a single file. It is popular for films and archives, but many phones, TVs and editors do not open it natively.
What is MP4?
MP4 is the most widely used video container. It usually carries H.264 or H.265 video with AAC audio, and it plays on practically every phone, browser, smart TV and editing program, which makes it the safest choice for sharing and uploading.
Tips for converting MKV to MP4
- Check the length and resolution of your MKV file first: long 4K videos take several minutes to process and may exceed the 50MB free limit.
- If you only need the soundtrack, pick an audio format such as MP3 instead of MP4 — the file will be much smaller.
- Keep the original video until you have checked the converted file plays correctly on the device you want to use.
- Subtitles and extra audio tracks are not always carried over between containers, so check them after converting.
Frequently asked questions
- How do I convert MKV to MP4 online?
- Upload your MKV file above, select MP4 as the output format, and click Convert. ConvertFastHub processes the file in the cloud and gives you a download link — no software installation required.
- Is it free to convert MKV to MP4?
- Yes. Free accounts get 10 conversions every 24 hours with files up to 50MB. For unlimited conversions, larger files up to 1.5GB, and priority processing, upgrade to ConvertFastHub Pro.
- Is my file safe when I convert it?
- Files travel over an encrypted connection, are scanned automatically for malware (files up to 200 MB), are processed in an isolated worker and are deleted automatically: after 1 hour without an account, 24 hours with a free account, or 7 days with Pro.
- Can I convert MKV to MP4 on my phone?
- Yes. The converter runs in the browser and the work happens on our servers, so it works the same on Android, iPhone, tablets and computers — there is no app to install.
- Do I need an account?
- No. You can convert without signing up; results are then kept for 1 hour. A free account keeps them for 24 hours and shows your conversion history.