Step 1: Supply your MP4 files using the button above or by haul and lay.
Step 2: Click the 'Convert' button to start the conversion.
Step 3: Get your converted MKV files.
MP4 to MKV Conversion FAQ
What does the MP4 to MKV converter do?
+
It transcodes a MP4 video into the MKV container. Resolution, frame rate, and aspect ratio are preserved by default — useful when you need a different format for a target player without quality loss.
Will resolution and frame rate be preserved in the MKV?
+
Yes. MP4 → MKV keeps resolution, frame rate, and aspect ratio unchanged by default. To change them, use the Resize or Speed tool on the result.
Is the MP4 to MKV conversion reversible?
+
You can convert the MKV back to MP4 on this site. If either format involved is lossy, the round-trip is not bit-perfect even though it is visually or audibly close.
Will the converted MKV be a different size than the MP4?
+
Modern codecs compress better, so MKV from a legacy MP4 is typically 30-60% smaller at equivalent quality. Conversions in the opposite direction can grow the file.
Why do so many people keep their libraries in MKV?
+
Because it was designed for keeping things rather than for delivering them. An MKV holds an unlimited number of audio tracks, selectable subtitle streams, chapter marks and cover art in one file, which is exactly what a disc rip needs somewhere to put — everything ends up in a single object instead of a folder of loose companions. The trade is playback: very little consumer hardware decodes it natively, so the same file that is ideal on a computer or a media server usually has to be converted again before a television will touch it. MKV is the archival container of choice because it stores unlimited audio tracks, soft subtitles, chapter markers and cover art in one file.
Can the MKV hold more than one audio track?
+
Yes, and it is a real upgrade over MP4. MKV treats every audio stream as a first-class track, so an original-language mix, a dub and a director commentary can live in one file with the player switching between them on demand.
Does MKV support chapter markers that MP4 did not?
+
It does. MKV stores chapters as container metadata, so a long recording can be navigated by section instead of by scrubbing a progress bar. MP4 has nowhere to put that information, so if the source shipped with a chapter list it was in a sidecar file — hand that to the converter and it gets written into the MKV.
Can I still embed the file on a web page after converting MP4 to MKV?
+
Not directly. MP4 plays inline in every browser; MKV does not, so a page embedding it falls back to a download link or an empty player frame. If the file is destined for a website, keep the MP4 for the web and treat the MKV as the archive or editing copy. MKV has almost no native hardware support — phones, browsers and TVs usually need VLC or a remux before they will play it.
Will the MKV still play smoothly on a phone or a TV?
+
It may not. MP4 is decoded by dedicated silicon on phones, tablets and TVs, which is why it plays without flattening the battery. MKV typically falls back to software decoding on the same hardware — higher CPU load, a warmer device, and dropped frames on 4K material. For a device target, MP4 is the safer container to stay in.
Both MP4 and MKV are modern containers — which should I actually keep?
+
Keep whichever matches where the file is going, because neither is better in the abstract. One of these two is built for playback compatibility and the other for holding everything a file might contain, and they trade against each other exactly along that line. The pragmatic answer for most libraries is to archive in the feature-rich container and export to the compatible one on demand. MP4 is the safest possible delivery target — every phone, browser, console, editor and Smart TV built in the last decade plays it without extra software.
Is there a file-size limit when converting MP4 to MKV?
+
Anonymous uploads are capped at a generous default; signed-in free accounts get a higher cap, and Pro accounts have no per-file limit. Browser memory is usually the practical constraint long before our server-side limits kick in.
Can I batch-convert several MP4 files to MKV at once?
+
Yes. Drop or pick multiple MP4 files in one upload — the converter processes them in parallel and returns a ZIP of the MKV results. There is no need to repeat the upload step per file.
