Convert your .mkv files to .webm format online for free. No software to install. Fast, secure, and easy.
Pro account required for audio & video
Drag and drop your .mkv file or click to browse.
Select WebM as your output format.
Click Convert and download your .webm file.
MKV is a legacy format with limited compatibility on modern devices. Converting to WebM ensures your video can be played on any modern device, shared on social media, and embedded in web pages without compatibility issues.
MKV (Matroska Video, introduced in 2002) uses proprietary compression. WebM (Web Media, introduced in 2010) uses proprietary compression. MKV browser support: Limited (Chrome/Edge for VP8/VP9/AV1 in WebM subset). WebM browser support: All modern browsers (Chrome, Firefox, Edge; Safari with AV1 only).
The quality impact depends on the specific settings used during conversion. WebM uses compression that may affect quality depending on the chosen settings.
Typical MKV file size: A 2-hour 1080p H.265 movie: ~4-8 GB; 4K remux: ~40-80 GB. Typical WebM file size: A 1-minute 1080p VP9 video: ~10-20 MB.
VP9 encoding is significantly slower than H.264 but produces comparable quality at lower bitrates. Use the "good" quality preset with CRF 31-33 for a solid balance of quality and file size. For maximum quality, use two-pass encoding.
Convert MKV to WebM with 3 free conversions per day. No hidden fees.
Create a free account in 10 seconds and start converting immediately. No credit card required.
Files are encrypted during transfer, processed on secure servers, and deleted immediately after conversion.
Convert files from any device — desktop, tablet, or phone. No software to install, works in any modern browser.
SquishConvert supports over 358 file conversion combinations across images, documents, audio, and video.
Your converted .webm file maintains the best possible quality. No unnecessary compression or quality loss.
Video conversion requires a Pro account. See pricing — starting at $4.99/month
You get 3 free conversions per day. Video conversions require a Pro account.
Most files convert in under 10 seconds. Larger files may take a bit longer depending on size.
Yes. Files are encrypted during transfer, processed on secure servers, and deleted immediately after conversion. We never store your files.
Currently, SquishConvert converts one file at a time. Batch conversion is coming soon — stay tuned!
Free users can convert files up to 10 MB. Pro users can convert files up to 500 MB.