MKV to MP4 (H.264) - Online Video Converter
Convert MKV to MP4 (H.264) online. Private, client-side - no uploadrequired. Batch conversion, quality presets, codec control.
About MKV to MP4 (H.264)
MKV is an open container holding multiple video, audio, and subtitle tracks in one file. MP4 repackages the picture as H.264 with AAC sound for universal playback across phones and browsers. Only the selected tracks carry over, so pick audio languages and subtitles before converting. Embedded fonts and chapters stay behind, since the target keeps a simpler structure. Where codecs already match, stream copy avoids re-encoding; otherwise the picture re-encodes with small losses at high bitrates.
Why convert MKV to MP4 (H.264)?
- Smaller files with MP4 lossy compression.
- Keep animation and transparency where supported.
- Private, no upload - runs in your browser.
MKV vs MP4 (H.264)
| Animation | Yes | Yes |
|---|---|---|
| Transparency | Yes | No |
| Compression | lossy | lossy |
| Typical use | MKV is an open container holding multiple video, audio, and subtitle tracks. | MP4 pairs H.264 video with AAC audio in the ISO base media container. |
When not to convert MKV to MP4 (H.264)
- Skip MP4 for archival masters: lossy compression discards detail, so keep the MKV original.
- Flatten transparency first: MP4 has no alpha channel, so composite MKV over a background color.
Limits
Starting point: MKV - Multi-track container for video, audio, subtitles. Only the selected tracks carry over, so pick audio and subtitles first. H.264 has no alpha channel, so transparency is dropped. Encode MP4 (H.264 / AAC) from MKV at a bitrate near the source, and confirm the audio track before converting.
How conversion works
Conversion runs entirely in your browser with FFmpeg WASM. Files never leave your device.