How to convert WebM to Matroska (MKV)
- 1
Upload your file
Drag and drop a file or click to select one. Keep this page open while the file uploads and converts.
- 2
Convert WebM to Matroska (MKV)
NexMedia converts WebM to Matroska (MKV) on its own servers. Processing time depends on the file size and how busy the queue is.
- 3
Download the converted file
When the conversion finishes, the download appears on this page. Your converted file is kept for 2 hours, then deleted.
About WebM
WebM is an open, royalty-free video format developed by Google and based on the Matroska container. It holds VP8, VP9 or AV1 video with Vorbis or Opus audio.
It is made for the web: all major browsers play it in the HTML video element, and it is common for screen recordings and short clips.
WebM allows only its own small set of codecs, so H.264 video or AAC audio has to be re-encoded to fit.
Convert WebM to MKV online free, no account required — MKV is a flexible open container for video with any number of audio and subtitle tracks.
Change WebM to MKV without losing quality — convert WebM to MKV free in your browser.
Why can't I upload my WebM video to Instagram or TikTok? Social apps almost always demand MP4, so a WebM made for the web needs converting before it will upload.
About Matroska (MKV)
Matroska (MKV) is an open container format that can hold almost any video and audio codec, any number of audio and subtitle tracks, chapters and attachments.
It is popular for films and series with several audio languages and subtitle tracks, and for archiving video.
Many phones, browsers and TVs do not play MKV files directly, even when they support the codecs inside.
Why convert video to MKV? When one file must carry several audio languages, subtitle tracks and chapters, no container holds them as flexibly.
What changes when you convert WebM to MKV
- The WebM is re-encoded into MKV at the default quality settings, so the result looks close to the original but is not bit-identical.
Settings you can change
Before you convert WebM to MKV, you can adjust: Video codec, Rate control, Quality (CRF), Video bitrate, Resolution, Width, Height, Scale fit, Frame rate, Encoder preset, Audio codec, Audio bitrate, Trim start, Trim duration, and Remove metadata.
Limits
Each plan sets a maximum file size and a number of conversions per day, and video and audio files also have a maximum length. Guests can convert files up to 100 megabytes and 5 per day; a free account raises this to 500 megabytes and 25 per day; paid plans go up to 100 gigabytes.
Your converted MKV file is kept for 2 hours, then deleted.
WebM to MKV: questions and answers
Does converting WebM to MKV reduce quality?
The WebM is re-encoded into MKV at the default quality settings, so the result looks close to the original but is not bit-identical.
What is the difference between WebM and MKV?
WebM is an open, royalty-free web video format with VP8, VP9 or AV1 video and Opus or Vorbis audio. MKV is a flexible open container for video with any number of audio and subtitle tracks.
Can I change the settings when converting WebM to MKV?
Before you convert WebM to MKV, you can adjust: Video codec, Rate control, Quality (CRF), Video bitrate, Resolution, Width, Height, Scale fit, Frame rate, Encoder preset, Audio codec, Audio bitrate, Trim start, Trim duration, and Remove metadata.
Do I need an account to convert WebM to MKV?
No. You can convert WebM to MKV without an account; signing in raises the file-size and daily limits.
How long is my converted MKV file kept?
The MKV file you convert from WebM is kept for 2 hours, then deleted automatically.
When I convert WebM to MKV, is the video re-encoded?
The WebM is re-encoded into MKV at the default quality settings, so the result looks close to the original but is not bit-identical.
Will converting WebM to MKV change my original file?
No. The conversion reads your WebM and writes a new MKV file, leaving your original WebM file untouched.