FizzyTools
MP4 to MKV
Turn MP4 videos into MKV in your browser, in seconds. No upload, and no quality loss when the video can be copied.
How it works
- 1AddDrop your videos. Nothing is uploaded.
- 2CheckEach video shows whether it can be copied or needs new video.
- 3ConvertSave the result, checked and ready.
Questions
Does the quality change?
No. Most videos are copied into the MKV as they are. Rotated phone videos need new video, because MKV can't store the rotation.
Are my videos uploaded?
No. Your video is converted by your own device, in this page. Nothing is sent to us or anyone else, so a large file doesn't have to upload first, and private videos stay private.
What does "Copy, no quality loss" mean?
The picture and sound already suit the new format, so they move across unchanged. It takes seconds and nothing gets worse.
Will my iPhone video play on Windows?
iPhones record in HEVC, which some Windows PCs can't play. Choose Plays everywhere on the video's row: it makes H.264, which plays on almost everything.
Why am I asked about the sound?
Some sound formats, such as AC-3, E-AC-3 and DTS, can't be changed here. FizzyTools can only copy them unchanged, so you choose whether to copy the sound or convert without it.
Why has my video no sound in another player?
Not every player reads every sound format. Web browsers don't play AC-3 or E-AC-3, and Apple's apps show no sound for DTS in an MP4. Try another video app, or keep the video as MKV.
Can I convert a video from a link?
No. This tool only works on files on your device. Downloading videos from websites can break their terms and copyright law, so we don't offer it. Convert videos you made or have permission to use.
Can it convert copy-protected videos?
No. Copy-protected videos are refused, and FizzyTools doesn't remove copy protection.
Does the file keep my location?
No. Location and device details are removed, and the title and date stay. A switch keeps everything if you want it.
Is there a size limit?
Videos up to 10 GB, 50 at a time, and up to 3 hours when new video is needed. The result needs free space in your browser, and private windows have less.
Which browsers work?
Copying works in Safari 15.4, Chrome or Edge 100, and Firefox 115, or newer. Making new video needs Safari 16.4, Chrome or Edge 100, or Firefox 130, or newer.
Do I keep my original?
Yes. Your original isn't changed. We make a new copy.