MKV to MP4 Converter – Free Online

How to Convert MKV to MP4 Online

Upload your MKV file

Drag and drop your .mkv file onto the page or click to browse. You can select several MKV files at once to batch-convert them.

MP4 is preselected

The output format is already set to MP4, so you can convert immediately. If you need to, adjust the codec, resolution, frame rate or bitrate in the settings panel first.

Convert and download

Click Convert. The MP4 file is processed on your own device; nothing is uploaded to a server. When it finishes, click Download to save it (or Download all to get a batch as a ZIP).

Why Convert MKV to MP4?

MKV is a fantastic archival container but a poor playback one: Apple devices, most smart TVs, PowerPoint and every web browser refuse it. Converting MKV to MP4 keeps the same video and audio while switching to the container everything understands.

Our converter lets you choose which audio and subtitle tracks to keep from the MKV and re-encodes the video with the source codec and bitrate by default, so a two-hour film comes out looking the same; conversion time depends on the film's length and resolution.

Private by design: your MKV file is converted on your own device and never uploaded.
MP4 preselected: the output format is already chosen, so it is a one-click conversion.
Batch friendly: convert several MKV files in one go and download them as a ZIP.
No limits, no watermark: free for files of any size, with nothing stamped on the output.

MKV vs MP4

MKV (Matroska Video): MKV (Matroska) is an open container that can hold practically any codec plus multiple audio tracks, subtitle tracks and chapters, which makes it popular for archiving films and TV episodes. It is best for archiving, multi-language releases and media servers.

MP4 (MPEG-4 Part 14): MP4 is the most widely supported video container in the world. It usually carries H.264 or H.265 video with AAC audio, plays on every phone, browser, TV and editing app, and is the safest choice for sharing. It is best for sharing, social media, web playback and mobile devices.

In short: keep MKV when the priority is archiving, multi-language releases and media servers, and switch to MP4 when the file is headed for sharing, social media, web playback and mobile devices. Need a different target? The full Video Converter supports every format listed below.

MKV to MP4 FAQ

Do I lose the subtitles when converting MKV to MP4?

Text subtitles can be selected in the subtitle track picker and carried into the MP4 as soft subtitles. Image-based subtitles (PGS/VobSub) are not supported in MP4.

Is MKV to MP4 lossless?

Not bit-for-bit: the video is re-encoded, but with the source codec and bitrate kept (the default) the MP4 is visually the same as the MKV. VP9 or other codecs an MP4 player cannot handle are converted to H.264.

Why is my MP4 silent after conversion?

The MKV probably used an audio codec the target player cannot handle. Convert again and choose AAC as the audio codec, which plays everywhere.

Is this MKV to MP4 converter free?

Yes. Converting MKV to MP4 on MediaConverter.io is completely free, with no watermark, no sign-up and no daily conversion limit.

Are my MKV files uploaded to a server?

No. The converter runs inside your browser using WebAssembly and WebCodecs, so your .mkv file is read and converted on your own device. Nothing is uploaded, which keeps private recordings private and means there is no waiting in an upload queue.

Is there a file size limit for MKV to MP4?

No fixed limit. Because processing happens locally, the practical limit is your computer's memory and patience; multi-gigabyte MKV files convert fine on a desktop browser. Very large files take longer on phones.

Will converting MKV to MP4 reduce quality?

The video is re-encoded into MP4. Keep the source codec, resolution and bitrate (the defaults) and the result is visually the same as your MKV; lowering the bitrate or resolution is what reduces quality, and you control that trade-off in the settings panel.

Which browsers support the MKV to MP4 converter?

Current versions of Chrome, Edge, Firefox and Safari on desktop all work. Chrome and Edge are fastest because they expose hardware-accelerated WebCodecs decoders.