MKV to MP4 Converter

Turn an MKV into an MP4 that plays on phones, browsers, and TVs. Often a lossless container swap. Free, in your browser, with no signup.

Select MKV file →

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We support most file types including: MP4, MOV, WEBM, AVI, MP3, WAV, PNG, JPEG, GIF, MKV, PDF, FLAC, TIFF!

EchoWave is used by creators, marketers, educators, and businesses to convert and edit media online.

Updated June 2026

Convert an MKV to MP4 so it plays everywhere: phones, browsers, smart TVs, and almost any app or upload box. MKV holds the same video codecs MP4 does, so when the inside is already H.264 or H.265 the converter can repackage the streams into an MP4 container with no re-encoding and no quality loss. MP4 is the most widely supported video format there is, which is why it is the usual answer when an MKV will not open or upload. EchoWave does it in your browser, free and with no signup.

Free, no sign-upNo account, no trial

Runs in your browserNothing to install

Works on every devicePhone, tablet, laptop

No watermarkClean output, every time

How it works

How to convert MKV to MP4

1
Upload your MKV
Drag your MKV onto the converter or pick it from your device. Nothing to install.
2
Choose MP4 and convert
Select MP4 as the output and start. Free, with no sign-up and no watermark.
3
Download your MP4
Save the finished MP4, or open it in the editor to trim, crop, or resize it first.

Try it

Estimate your MP4

Pick a video bitrate and a length to see the MP4 file size before you convert.

Video bitrate

Length5 min

1 min30 min

Estimated MP4 size183MBSharp 1080p

An estimate. Real size varies with resolution, frame rate, and how much the picture moves.

The formats

MKV vs MP4

MKV

Matroska Video

An open container that holds almost anything

Type: Open video container
Holds: Almost any codec, plus several audio and subtitle tracks
Typical size: Large, depends on the codec inside
Plays on: VLC and most modern players, less on default phone apps

Best for:Movies with multiple audio tracks and subtitles

MP4

MPEG-4 Part 14

The video format that plays everywhere

Type: Video container
Holds: H.264 video plus AAC audio, sometimes subtitles
Typical size: Large, it carries video
Plays on: Phones, browsers, TVs, almost any player

Best for:Watching and sharing video

Will it lose quality?

When the codecs already match MP4, the converter can change the container without re-encoding, so the picture stays identical.
When the video has to be re-encoded for MP4, a high bitrate keeps it visually close to the MKV.
Converting cannot add detail the MKV never had. The output is at best as good as the source.

Use cases

What people use it for

Play anywhereMake a clip your device supports

Video editorsGet footage your software accepts

Web videoUse a format browsers play

CourseworkHand in a standard video file

SharingSend a clip people can open

Troubleshooting

If something looks off

The MP4 will not play

Some players are picky about codecs. Try it in VLC, which opens almost anything, or convert again and let the converter re-encode the video.

The file got larger

A format change can shift the size, and re-encoding at a high bitrate adds overhead. Lower the bitrate or trim the clip for a smaller file.

Audio and video drift out of sync

Re-download the source and convert again. If a long recording drifts, splitting it into shorter pieces usually fixes the sync.

FAQ

MKV to MP4 questions

Can MKV to MP4 be done without losing quality?

Often, yes. MKV and MP4 can both hold H.264 and H.265 video, so when the codecs already match MP4 the converter copies the streams into a new container instead of re-encoding them. That repackage, sometimes called a remux, is lossless and fast. A re-encode only happens when the source uses a codec MP4 does not support.

Why will my MKV not play but an MP4 would?

MKV is an open container that not every device or app recognises, especially default phone players, smart TVs, and social upload boxes. The video inside is usually standard, so swapping it into an MP4 container makes the same footage play in places that rejected the MKV.

Is the MKV to MP4 converter free?

Yes. EchoWave converts MKV to MP4 with no signup, no file-count limit, no trial, and no watermark. Upload your video, pick MP4, and download the result from your browser.

How do I convert MKV to MP4?

Upload your MKV, choose MP4 as the output format, and start. When it finishes, download the MP4 or open it in the editor to trim, crop, or resize it first.

What happens to multiple audio tracks and subtitles?

MP4 supports fewer tracks than MKV. The main video and audio convert cleanly, and a single subtitle or audio track usually carries across, but a stack of audio languages and embedded subtitles may not all survive. If you depend on all of them, keep the MKV as well.

Does the MKV to MP4 converter work on iPhone, Android, Mac, and Windows?

Yes. The converter runs in any browser, so it works on iPhone, iPad, Android, macOS, Windows, Chromebook, and Linux with nothing to install. MP4 then plays on essentially all of them.

Can I convert a large MKV movie to MP4?

Yes. There are no file-count limits, and large videos are supported. A long, high-resolution movie simply takes a little longer to upload and convert, and a lossless container swap is quicker than a full re-encode.

Is it safe to convert MKV to MP4 here?

It is. No account or download stands between you and the converter, and because a matching MKV remuxes into MP4 by copying the existing streams, your footage is repackaged rather than rebuilt from scratch. Read our security page to see how EchoWave handles the MKV you upload and the MP4 you get back.