How does the MP4 to MKV converter work?

Upload your MP4 files and start the conversion. FFmpeg copies every video, audio and subtitle stream into an MKV, keeping chapters and track languages.

Can I use the converter without signing up?

Yes. You can upload, convert and download without an account. Free use has a daily limit, and a $2.99 or $6.99 pass removes it, with no monthly subscription.

Are there file-size limits?

Each MP4 file can be up to 20GB.

Does this work in a mobile browser?

Yes. dragdropdo runs in Safari, Chrome and other mobile browsers on iPhone, iPad and Android, so you can convert MP4 files on a phone or tablet without installing an app.

Can I batch convert MP4 files?

Yes. Add several MP4 files to one job, then download each MKV file on its own or all of them together as a ZIP.

Is the video re-encoded?

No, the streams are copied unchanged, so quality stays the same. The exception is a phone video with a rotation flag: it's re-encoded upright as H.264 at high quality (x264 CRF 18), its sound is still copied, and HDR becomes SDR. If a track can't be stored in MKV, the file is converted to H.264 and AAC instead.

Yes. MP4 text subtitles are stored as SRT tracks in the MKV. Chapters and track languages are kept too.

What happens to multiple audio tracks?

Every audio track is copied unchanged, in its original codec and with its language, so language and commentary tracks stay available.

Will the MKV be the same size?

About the same. Container overhead differs slightly, but the streams are copied. Only rotated phone videos are re-encoded.

Timecode tracks, data tracks and cover art are dropped. All video, audio and subtitle tracks stay.

Why use MKV instead of MP4?

MKV holds more codecs and subtitle types, attached fonts and unlimited tracks, which makes it a favorite for media servers and archives.

How does the MP4 to MKV converter work?

Upload your MP4 files and start the conversion. FFmpeg copies every video, audio and subtitle stream into an MKV, keeping chapters and track languages.

Can I use the converter without signing up?

Yes. You can upload, convert and download without an account. Free use has a daily limit, and a $2.99 or $6.99 pass removes it, with no monthly subscription.

Are there file-size limits?

Each MP4 file can be up to 20GB.

Does this work in a mobile browser?

Yes. dragdropdo runs in Safari, Chrome and other mobile browsers on iPhone, iPad and Android, so you can convert MP4 files on a phone or tablet without installing an app.

Can I batch convert MP4 files?

Yes. Add several MP4 files to one job, then download each MKV file on its own or all of them together as a ZIP.

Is the video re-encoded?

No, the streams are copied unchanged, so quality stays the same. The exception is a phone video with a rotation flag: it's re-encoded upright as H.264 at high quality (x264 CRF 18), its sound is still copied, and HDR becomes SDR. If a track can't be stored in MKV, the file is converted to H.264 and AAC instead.

Yes. MP4 text subtitles are stored as SRT tracks in the MKV. Chapters and track languages are kept too.

What happens to multiple audio tracks?

Every audio track is copied unchanged, in its original codec and with its language, so language and commentary tracks stay available.

Will the MKV be the same size?

About the same. Container overhead differs slightly, but the streams are copied. Only rotated phone videos are re-encoded.

Timecode tracks, data tracks and cover art are dropped. All video, audio and subtitle tracks stay.

Why use MKV instead of MP4?

MKV holds more codecs and subtitle types, attached fonts and unlimited tracks, which makes it a favorite for media servers and archives.

Free MP4 to MKV Converter Online

Convert MP4 to MKV online with every audio track, subtitle and chapter kept, usually without re-encoding. Upload files up to 20GB and download the converted result in a few clicks.

Convert MKV to MP4

Drag & Drop your MP4 file here

MP4 files, up to 20GB

Files stay private.

Automatically deleted after 24 hours.

Link 20GB upload limit.

4.8/5

Trusted for 1,827,796+ conversions

HOW IT WORKS

Convert MP4 to MKV in three steps

Three steps, no account, nothing to install.

Upload your MP4 files

Drag in .mp4 videos from a phone, camera, download or editing export.

Convert to MKV

Start the conversion. The streams are copied into MKV unchanged, and text subtitles become SRT tracks.

Download the MKV

Download each MKV, or several together as one ZIP.

MP4

MP4 is the most widely supported video format, playing in every browser, phone, TV and editing app.

MKV

MKV is the open Matroska container, able to hold any codec plus many audio and subtitle tracks in one file.

FILE FORMATS

MP4 and MKV compared

SOURCE

MP4

MPEG-4 Part 14 is the default container for phone recordings, web video and streaming. MP4 with H.264 video and AAC sound plays on iPhone and Android, in every browser, on smart TVs and in Windows and Mac players without extra codecs. It holds text subtitles and chapters, but not picture-based subtitles.

TARGET

MKV

Matroska started in 2002 as an open, royalty-free container. An MKV can carry almost any video and audio codec, several language tracks, text and picture subtitles, chapters and even attached fonts. That flexibility makes it the favorite for film backups and recorders, though iPhones, Safari and some TVs won't play it.

Feature	MP4	MKV
Developed by	MPEG (ISO)	Matroska (open standard)
File extension	.mp4	.mkv
Usual video codec	H.264, HEVC, AV1	Any: H.264, HEVC, VP9, AV1
Usual audio codec	AAC	Any: AAC, AC-3, DTS, FLAC, Opus
Subtitles	Text only	Yes, many tracks
Best for	Sharing and playback anywhere	Movies and multi-track archives
Plays on phones and browsers	Yes	VLC, most TVs; not iPhone

USE CASES

Use Cases for MP4 to MKV

When MKV suits your player, server or archive better than MP4.

Prepare files for Plex, Jellyfin or Kodi

Media servers handle MKV tracks, languages and chapters cleanly.

Add more subtitle tracks

Once in MKV, add SRT or ASS subtitles with MKVToolNix.

Keep commentary and language tracks together

Every audio track is copied with its language.

Archive videos without quality loss

Streams are copied, so the MKV is identical in quality.

Edit tracks with MKVToolNix

Rename, reorder or remove tracks once the file is MKV.

Fix rotated phone videos for players that ignore rotation

Phone clips with a rotation flag are re-encoded upright, so every player shows them correctly.

Standardize a film library

Keep a collection in one container.

Play on an Android TV box

Android boxes and Kodi builds favor MKV.

Attach fonts for styled subtitles

MKV can carry fonts for ASS subtitles you add later.

Work around MP4 limits

MKV accepts codecs and subtitle types that MP4 can't hold.

SUPPORTED FILES

Which MP4 Files Can I Convert?

MP4 files from any common source are supported.

H.264, HEVC and AV1 MP4

Video is copied as it is.

Multi-track MP4

Every audio and subtitle track is kept, with languages.

Phone recordings

Clips with a rotation flag are re-encoded upright as H.264.

Files with chapters

Chapter marks are kept in the MKV.

A batch

Upload several MP4s and download the MKVs as a ZIP.

TROUBLESHOOTING

MKV Not Playing Right?

These are the usual causes.

The MKV won't play on an iPhone

Apple devices don't play MKV natively. Use VLC or Infuse, or keep the MP4.

A phone video looks different

Rotated phone clips are re-encoded upright. HDR footage becomes SDR in that case.

Cover art is gone

MP4 cover art, timecode and data tracks are dropped. Video, audio and subtitles are kept.

The size is almost identical

That's expected. The streams are copied, not re-encoded.

A track looks different in my player

Some players only show the default track. Choose others in the player's audio or subtitle menu.

Still not working

If the MP4 plays but the MKV doesn't, try VLC, which reads every MKV variant.

COMPARISON

dragdropdo vs. Desktop Video Converters

HandBrake, VLC and FFmpeg give you every setting once installed. dragdropdo is built for turning MP4 into MKV with sensible settings already chosen, from any device.

What matters	dragdropdo	Desktop Video Converters
Nothing to install	✓Yes. Runs in any modern browser.	~Yes, a download. FFmpeg also needs the command line.
Works on phones and tablets	✓Yes. Desktop, Android, iPhone and iPad.	~Mostly desktop only.
Batch conversion	✓Yes. Add many files and download one ZIP.	~HandBrake has a queue; FFmpeg needs scripts.
Share finished files	✓Yes. Send a unique link from the result page.	~You upload and share the files yourself.
Pricing	✓Free with daily limits. $2.99 or $6.99 passes for unlimited use, no monthly plan.	~Free (HandBrake, VLC, FFmpeg).
Quality and size settings	✓Chosen for you for MKV, with nothing to tune.	~Yes. Full control over codecs, bitrate and resolution.

Other tools use different pricing, limits and workflows. This comparison describes dragdropdo's own features without assuming every other tool works the same way.

1.8M+

Files converted

and counting

4.8

Average rating

from our users

~4s

Avg. conversion

per file

Files kept

Auto-delete in 24h

WHY DRAGDROPDO

Built to be quick, safe, and free

Convert MP4 to MKV in your browser, with nothing to install and nothing kept after 24 hours.

Private by default

Files are encrypted in transit and deleted from our servers automatically after 24 hours.

No install required

Convert in any modern browser on Windows, Mac, Linux, Android, iPhone or iPad. No app and no sign-up wall.

Big files and batches

Upload files up to 20GB each, add several at once, and download the results one by one or as a ZIP.

Share & download

Save finished files to your device or pass them on with a share link from the result page.

MORE MP4 TOOLS

Explore our other video operations

MP4, or MPEG-4 Part 14, is a digital multimedia format used to store video, audio, subtitles, and images. Its versatility and compatibility across devices make it a preferred choice for video streaming and file sharing. MP4 offers excellent compression for high-quality playback, making it ideal for online content, mobile use, and professional video editing. Optimize your digital media experience with the MP4 format.

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