How do I convert WebM to MKV?

Drop your WebM file onto the converter above, make sure MKV is selected, and click Convert. When it's done, download the MKV file — it usually takes a few seconds.

Is it safe to convert WebM to MKV here?

Yes. WebM to MKV conversion happens entirely inside your browser using WebAssembly, so your file is never uploaded to any server.

Is the WebM to MKV converter free?

Yes — free with no watermark. Signed-out visitors can convert 25 files a day, and a free account raises that to 250.

Will converting WebM to MKV reduce quality?

No — MKV preserves the content of your WebM file as faithfully as the format allows.

Can I convert multiple WebM files at once?

Yes. Add up to 5 files at a time without an account, 10 with a free account and up to 500 on paid plans, then download them individually or as a single ZIP.

Can I convert MKV back to WebM?

Yes — use our MKV to WebM converter. Note that converting back and forth between formats can't recover detail lost to lossy compression.

MKV→WebM WebM→MP4 MP4→MKV WebM→MP3 MOV→MKV WebM→WebP GIF→MKV WebM→MOV WebM→GIF AVI→MKV WebM→WAV WMV→MKV WebM→M4A WebM→AVI WebM→FLAC WebM→AAC WebM→OGG WebM→WMV WebM→Opus WebM→M4V WebM→FLV WebM→MPEG WebM→3GP WebM→WMA WebM→TS WebM→MPG WebM→AIFF WebM→AMR WebM→VOB WebM→M4B M4V→MKV 3GP→MKV FLV→MKV MPEG→MKV TS→MKV MPG→MKV MTS→MKV VOB→MKV M2TS→MKV APNG→MKV OGV→MKV MXF→MKV DivX→MKV 3G2→MKV RM→MKV RMVB→MKV F4V→MKV ASF→MKV PNG→JPG JPG→PNG PNG→WebP JPG→WebP WebP→PNG WebP→JPG HEIC→PNG HEIC→JPG MP4→MP3 PNG→JPEG JPG→JPEG JPEG→PNG JPEG→JPG PNG→PDF JPG→PDF PDF→PNG PDF→JPG HEIC→WebP MP4→WebP PDF→DOCX DOCX→PDF JPEG→WebP WebP→JPEG PNG→GIF JPG→GIF GIF→PNG GIF→JPG MP4→MOV MOV→MP4 WebP→PDF HEIC→JPEG WebP→GIF GIF→WebP HEIC→PDF MP3→WAV WAV→MP3 JPEG→PDF PDF→JPEG SVG→PNG SVG→JPG HEIC→GIF MOV→MP3 MP4→GIF GIF→MP4 JPEG→GIF GIF→JPEG PNG→AVIF JPG→AVIF AVIF→PNG AVIF→JPG MP3→M4A M4A→MP3 GIF→PDF SVG→PDF PNG→SVG JPG→SVG PDF→SVG SVG→WebP MOV→WebP MP4→WAV MP4→WebM WebP→AVIF AVIF→WebP WebP→SVG SVG→JPEG MKV→MP4 HEIC→AVIF MP4→M4A JPEG→AVIF AVIF→JPEG JPEG→SVG MOV→GIF GIF→MOV AVIF→PDF MP3→FLAC FLAC→MP3 MP4→AVI AVI→MP4 MKV→MP3 GIF→AVIF AVIF→GIF SVG→GIF GIF→SVG MOV→WAV XLSX→PDF CSV→PDF EPUB→PDF PDF→EPUB MOV→WebM MKV→WebP PNG→ICO JPG→ICO ICO→PNG ICO→JPG MP3→AAC WAV→M4A AAC→MP3 M4A→WAV MP4→FLAC AVI→MP3 MKV→MOV MOV→M4A DOCX→EPUB EPUB→DOCX CSV→DOCX PDF→TXT DOC→PDF TXT→PDF WebP→ICO ICO→WebP PPTX→PDF AVI→WebP

WebMMKV

Convert WebM to MKV

Free and private: WebM files are converted in your browser on computers; on phones, in our fast cloud and deleted automatically.

In your browser (fast cloud on phones)
No watermark
Batch & ZIP download

Need a smaller WebM? Compress WebM

How to convert WebM to MKV

1
Add your WebM files
Drag and drop WebM files onto the converter, paste them, or click to browse. You can add several at once.
2
Choose MKV
MKV is already selected. Open Options if you want to change quality, size or metadata.
3
Convert
Click Convert. Your files are converted right in your browser in seconds.
4
Download your MKV
Download each MKV file, or everything at once as a ZIP.

WebM vs MKV

From

WebM · WebM Video

WebM is an open, royalty-free video format designed for the web, using VP8/VP9 or AV1 video with Opus audio.

Type: Video
Extension: .webm
MIME: video/webm
Best for: video on websites and in browsers

Lossy compressionOpen standard

All WebM conversions →

MKV · Matroska Video

MKV is a flexible open container that can hold unlimited video, audio and subtitle tracks in nearly any codec.

Type: Video
Extension: .mkv
MIME: video/x-matroska
Best for: movies and series with multiple audio and subtitle tracks

Open standard

All MKV conversions →

Need it the other way around? Convert MKV to WebM.

WebM to MKV: frequently asked questions

Free, private and in your browser