Convert MKV to MP4 online — free
MKV won't play on your phone or smart TV? Convert to universal MP4 in one click.
- No watermarks
- Works on mobile
- First fix free, no signup
FixTheFile AI Studio- 1Upload
- 2Pick a fix
- 3Download
- 1Upload
- 2Pick a fix
- 3Download
Drop any file. AI picks the fix.
Images, audio, video, PDF, Word and ZIP — up to 500MB. Or click anywhere to browse.
image → upscale · audio → clean noise · video → extract audio · pdf → text · zip → repair
How it works
How to convert MKV to MP4
Upload your MKV file
Any Matroska video file, up to 500MB.
Select "Convert format"
FixTheFile converts to MP4 using FFmpeg.
Download your MP4
Plays on iPhone, Android, smart TVs, and browsers.
Why FixTheFile
Fast, reliable MKV to MP4 conversion
Universal playback
MP4 works everywhere MKV doesn't — phones, TVs, social media.
No VLC or codec packs
Convert directly in your browser.
Free first fix
No signup required to try.
Keeps audio and subtitles
Standard tracks are carried over during conversion.
Private processing
Files are never reviewed by humans.
Also compresses video
Shrink the MP4 afterward if it's still too large.
How do I convert MKV to MP4 for free?+
Upload your MKV to FixTheFile and select Convert format — it downloads as MP4.
Why won't MKV play on my phone or TV?+
Many phones, smart TVs, and browsers don't support the MKV container natively — MP4 is far more universal.
Will video quality change?+
FixTheFile re-encodes the video stream; quality is preserved at a comparable bitrate.
What's the max file size?+
Up to 500MB per upload.
Can I convert to other formats too?+
Yes — MOV and WEBM are also available from the same tool.
Ready to get started?
No software needed. Works on any device. First fix is free.
Convert MKV to MP4 free