MP4 to MKV Converter
Turn MP4 into the flexible MKV container for subtitles, multiple tracks and archiving — lossless, no signup, no watermark.
up to 50 files at once
auto-delete in 24h · no signup · no watermark
Command Palette
Search for a command to run...
How to convert MP4 to MKV online
- Click "Browse Files" or drag your MP4 file into the converter above (up to 200 MB free, 500 MB with an account).
- The target format is preset to MKV — adjust quality options in the picker if you need to.
- Hit "Convert". Your file uploads over an encrypted connection and converts automatically in the cloud — nothing to install.
- Click the green "Download" button to save your MKV file. The original is deleted immediately and the result auto-deletes after 24 hours.
That is the entire flow — no email address, no software install, no watermark on the output. The page you are reading handles MP4 to MKV from start to finish.
What's the difference between MP4 and MKV?
MP4 (MPEG-4 Part 14) and MKV (Matroska Video) solve different problems: MP4 is a media container format built for universal video playback and sharing, while MKV is a media container format whose strength is movie archives, multi-audio/subtitle videos. In practice you will meet MP4 when dealing with universal video playback and sharing, and reach for MKV when you need movie archives, multi-audio/subtitle videos — the table below compares them point by point.
| MP4 | MKV | |
|---|---|---|
| Full name | MPEG-4 Part 14 | Matroska Video |
| Developed by | MPEG (ISO/IEC) | Matroska.org (open source) |
| Released | 2001 | 2002 |
| Compression | Media container | Media container |
| Typical use | universal video playback and sharing | movie archives, multi-audio/subtitle videos |
| File extension | .mp4 | .mkv |
| MIME type | video/mp4 | video/x-matroska |
Why convert MP4 to MKV?
MP4 (MPEG-4 Part 14) is a multimedia container standardized in 2001 that bundles video, audio, and subtitles in one file. Usually carrying H.264 video with AAC audio, it is the most compatible video format in existence — every phone, browser, TV, and editor plays MP4. Here is when MKV is the better choice:
- →MKV holds unlimited audio and subtitle tracks — ideal for movie libraries.
- →It runs in the cloud — 10 free conversions a day with files up to 200 MB (20/day and 500 MB with a free account) — so even a phone or an old laptop converts at full speed.
Before you convert: three quick tips
- ●Video conversion time scales with length — for long footage, trimming to the segment you need before converting saves both time and quota.
- ●Posting to social platforms? MP4 is the universally accepted choice. Short looping clips? GIF. Embedding on a web page you control? WebM is worth considering.
- ●Keep your original MP4 — conversion never modifies it, and if you later need a different target format, starting from the original always gives the best quality.
MKV conversion settings explained
Filevo encodes video with H.264 at CRF 23 using the veryfast preset, with faststart enabled — the engineering balance of compatibility, quality, and speed: the output plays on any device and starts instantly when streamed.
The audio track is encoded as AAC at 128 kbps (higher available in options). Resolution matches the source, auto-adjusted to even dimensions as the encoder requires.
How the conversion works
Filevo's MP4 to MKV conversion is powered by FFmpeg, the open-source media framework behind much of the world's video infrastructure. We run it with compatibility-first settings tuned for everyday playback, and stream progress back to your browser in real time. Because everything runs in the cloud, your device's CPU stays idle — the browser only uploads and downloads.
Why convert MP4 to MKV?
MKV (Matroska) is an open, do-everything container. Where MP4 keeps things simple, MKV is built to hold extras: several audio tracks (multiple languages or commentary), multiple subtitle tracks, chapters, and attachments — all in one file. That makes it the format of choice for archiving movies and building media libraries. If you want a single, self-contained file that keeps every track and subtitle together, MKV is the container for the job.
Lossless remux: MP4 to MKV with zero quality change
MKV can carry the same H.264 video and AAC audio that an MP4 already contains, so this conversion is a remux, not a re-encode: Filevo copies the streams bit-for-bit into the Matroska container in seconds. There’s literally zero quality loss, the file size barely changes, and it’s far faster than tools that re-compress. You’re changing the box, not the contents.
MKV for archiving — but mind the compatibility
MKV’s flexibility is perfect for storage, Plex/Jellyfin libraries and anything where you want to preserve every track. The honest trade-off is reach: MKV isn’t as universally supported as MP4 — iPhones, many smart TVs, social platforms and some browsers won’t play it without help. So convert to MKV when you’re archiving or running a media server; keep MP4 when you need to share or stream to everyday devices.
Convert MP4 to MKV on any device
On Windows or Mac: drag the MP4 straight from Explorer or Finder into the converter above. On iPhone or Android: open this page in your browser, tap Browse Files and pick the MP4 — no app required. Because it’s a remux, even a large movie finishes quickly, and the MKV downloads ready for your library.
What is MP4?
MP4 (MPEG-4 Part 14) is a multimedia container standardized in 2001 that bundles video, audio, and subtitles in one file. Usually carrying H.264 video with AAC audio, it is the most compatible video format in existence — every phone, browser, TV, and editor plays MP4.
| Full name | MPEG-4 Part 14 |
| Developer | MPEG (ISO/IEC) |
| Released | 2001 |
| MIME | video/mp4 |
What is MKV?
MKV (Matroska Video) is an open-source container format released in 2002 that can hold unlimited video, audio, and subtitle tracks in one file. Loved for movie archiving and high-quality rips, it is not supported by iPhones, many TVs, and most editing apps — hence the constant MKV-to-MP4 conversions.
| Full name | Matroska Video |
| Developer | Matroska.org (open source) |
| Released | 2002 |
| MIME | video/x-matroska |
Filevo vs other MP4 to MKV converters
An honest comparison — CloudConvert and Convertio are capable tools; here is where Filevo differs:
| Filevo | CloudConvert | Convertio | |
|---|---|---|---|
| Free tier | 10/day | 10/day | 10 credits/day |
| No signup needed | Yes | Yes | Yes |
| Watermarks | None | None | None |
| Ads on free tier | No | No | Yes |
| Pricing model | 1 file = 1 credit, shown upfront | Per conversion minute | Credit packs |
Privacy & file security
Filevo deletes your uploaded MP4 file immediately after conversion and removes the converted MKV within 24 hours. Everything travels over TLS encryption, processing is fully automated with zero human access, and your files are never used for AI training. See our Privacy Policy for details. Privacy Policy →
MP4 to MKV converter FAQ
How do I convert MP4 to MKV for free?
Drop your MP4 file into the converter at the top of this page, confirm MKV as the target, click Convert, and download the result. It is genuinely free: 10 free conversions a day with files up to 200 MB (20/day and 500 MB with a free account), no watermarks, no software to install, no account required.
Is it safe to convert MP4 files online?
Yes. Transfers are TLS-encrypted end to end, and conversion is fully automated — no human ever sees your files. Your uploaded MP4 is deleted the moment conversion finishes, and the converted MKV auto-deletes after 24 hours (you can delete it sooner). We never use your files for AI training or share them with anyone.
Will I lose quality converting MP4 to MKV?
Video is re-encoded with H.264 at CRF 23 (veryfast preset) — a quality level that is visually indistinguishable from the source for normal viewing. Keep your original file if you need a frame-perfect master.
How long does MP4 to MKV conversion take?
It depends on length and resolution: short clips typically finish in well under a minute, while longer videos process at roughly real-time speed or faster. Upload time depends on your connection — for large files, uploading is usually the longest step.
Can I convert MP4 to MKV on iPhone or Android?
Yes. Filevo runs entirely in the browser, so it works the same on iPhone, Android, tablets, and computers — no app to install. On mobile, tap Browse Files to pick from your photos or files.
What's the maximum file size?
Anonymous conversions accept files up to 200 MB; a free account raises that to 500 MB. Paid plans go from 1 GB up to 10 GB per file, with higher daily limits and priority queues.
Can I convert multiple files at once?
Yes. Drop up to 50 files at once — they roll through the queue automatically. Pick a target format per file or set one per category, then download results individually or grab everything as a single ZIP.
What codec does the converted MP4 use?
Filevo encodes MP4 with H.264 video and AAC audio with the faststart flag — the most compatible combination, optimized to start playing instantly when streamed.
Does converting MP4 to MKV lose any quality?
No. MKV holds the same H.264/AAC streams as your MP4, so Filevo remuxes them — copied bit-for-bit into the new container with no re-encoding. The video and audio are identical to the source; only the wrapper changes.
What does MKV give me that MP4 doesn’t?
MKV handles multiple audio tracks, multiple subtitle tracks, chapters and attachments far more flexibly than MP4, all in one self-contained file. That’s why it’s favored for archiving movies and media-server libraries where you want to keep everything together.
Will my MKV play everywhere my MP4 did?
Not quite. MKV is less universally supported — iPhones, many TVs and social platforms may not play it without extra software. It’s ideal for archiving and media servers like Plex; for broad sharing and streaming, keep an MP4.
Whether you need movie archives, multi-audio/subtitle videos or simply a file that works where MP4 will not open, the converter above turns MP4 into MKV in seconds — free, private, and with nothing to install. Bookmark this page for the next time a MP4 file refuses to cooperate.
Last updated: 2026-07-27