Convert your .mp4 files to .mkv format online for free. No software to install. Fast, secure, and easy.
Pro account required for audio & video
Drag and drop your .mp4 file or click to browse.
Select MKV as your output format.
Click Convert and download your .mkv file.
Converting MP4 to MKV provides the most flexible container for multiple audio and subtitle tracks. MP4 (MPEG-4 Part 14) and MKV (Matroska Video) use different container structures with different strengths.
MP4 (MPEG-4 Part 14, introduced in 2001) uses proprietary compression. MKV (Matroska Video, introduced in 2002) uses proprietary compression. MP4 browser support: Universal. MKV browser support: Limited (Chrome/Edge for VP8/VP9/AV1 in WebM subset).
The quality impact depends on the specific settings used during conversion. MKV uses compression that may affect quality depending on the chosen settings.
Typical MP4 file size: A 1-minute 1080p H.264 video: ~15-30 MB; 4K: ~50-100 MB. Typical MKV file size: A 2-hour 1080p H.265 movie: ~4-8 GB; 4K remux: ~40-80 GB.
For the best conversion results, always start from the highest quality source file available. Converting from a previously compressed file compounds any existing compression artifacts. When in doubt, use higher quality settings — you can always re-convert at lower quality later, but you cannot recover quality that has been lost.
Convert MP4 to MKV 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 .mkv 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.