MKV to MP4 Converter – Free Online

How to Convert MKV to MP4 Online

Drop your MKV file

Drag and drop your .mkv file onto the box above, or click Choose Files. The request is already filled in: “Convert this to MP4”.

Say how, if you want

The AI assistant uses sensible defaults. To choose the resolution, frame rate or bitrate yourself, say so in the request, for example “Convert this to MP4 in 720p”.

Save your MP4 file

The assistant opens with your file and converts it on your own device; the file itself is never uploaded. When the MP4 file is ready, click Save. Prefer to set everything by hand, or batch-convert several files into a ZIP? The classic converter is one click away on this page.

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 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 already asked for: the AI assistant's request says MP4, so one drop does it. Want a particular resolution, frame rate or bitrate? Just say so.
Batch friendly: the classic converter on this page takes several MKV files in one go and downloads them as a ZIP.
Free, no watermark: no sign-up, and 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?

In the classic converter on this page, 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 free, with no watermark and no sign-up. The AI assistant runs on a free daily allowance of assistant credits; the classic converter on this page has no daily limit at all.

Are my MKV files uploaded to a server?

No. The conversion runs inside your browser using WebCodecs and FFmpeg compiled to WebAssembly, so your .mkv file is read and converted on your own device and never uploaded, which keeps private recordings private and means there is no waiting in an upload queue. The AI assistant only sees what you type and basic facts about the file: its name, format, duration and size.

Is there a file size limit for MKV to MP4?

There is no plan or account limit, but the converter loads the whole MKV file into your browser's memory, so about 2 GB per file is the practical ceiling; larger files may fail to open. Long or high-resolution files also take longer, especially on phones.

Can I choose the MP4 settings myself?

Yes. Ask the AI assistant for a resolution, frame rate or bitrate in your request. Audio and subtitle track selection, the codec list and every other setting are in the classic converter, one click away on this page.

Will converting MKV to MP4 reduce quality?

The video is re-encoded into MP4. Keep the source codec, resolution and bitrate (the defaults) and an ordinary 8-bit video is visually the same as your MKV, while a 10-bit, HDR or full-color (4:2:2 or 4:4:4) source can lose some color detail. Lowering the bitrate or resolution is what reduces quality, and you control that trade-off by asking for it (or in the classic converter's settings).

Which browsers support the MKV to MP4 converter?

It is built and tested on current desktop Chrome and Edge, which are also fastest because they expose hardware-accelerated WebCodecs video decoders. Recent Firefox and Safari releases support the same web APIs; if a file fails there, try Chrome or Edge.