How to Convert MOV and MKV to MP4
Use All Free Video Converter to create an MP4 copy of a local MOV or MKV video. Both tasks use the MP4 output profile; the input container and codecs determine what the program can read.
Choose a source, select MP4 and check the output
These steps create a new output file. Keep your source until the MP4 meets your needs.
Add a local MOV or MKV
Open All Free Video Converter and add the video from your PC. Keep the original. Check that the source plays with the expected sound before you start the conversion.
Select an MP4 H.264/AAC profile
Choose MP4 with H.264 video and AAC audio. Review the output resolution and frame rate. Keep the source values unless you need a smaller frame or a specific device setting.
Convert and test the new file
In Output settings, scroll down to Save to. Click Browse... and choose the output folder in the Windows folder dialog. Click Save settings, return to the main window and click Convert. Open the completed MP4 in your intended player and check the picture, sound and timing.
Example: MOV and MKV converted to MP4
On 14 October 2026, version 8.1.0 converted two self-made clips, one MOV and one MKV, to MP4 in the same batch. Each source used H.264 video and AAC audio and was about four seconds long. Both MP4 outputs contained H.264/AAC at 640 × 360 and 25 fps. Both jobs displayed Completed, and both full outputs passed a decoding check.
Join files was off, so the clips produced separate outputs. The two inputs shared the same base filename; in this test, the second MP4 received a (1) suffix. This checks these source codecs and a short single-audio-track clip, not every codec or embedded track that a MOV or MKV container can hold.
What differs between MOV and MKV?
Converting MOV to MP4
A MOV file may come from a camera or an editing tool. After conversion, check the visible orientation and make sure the audio still matches the picture.
Converting MKV to MP4
An MKV can include several audio tracks and subtitles. Check the finished MP4 for the tracks you require; do not assume all embedded content is retained.
Container and codec
MOV, MKV and MP4 are container names. A filename does not tell you every video or audio codec inside. A particular source can still be unsupported or damaged.
Resolve common MOV and MKV conversion problems
- The input will not open: check the source in another player, confirm that it is a complete local file, and try another MOV or MKV to isolate the problem.
- The MP4 has no sound: first check sound in the original. Then review the output audio settings and test the new file in a second player.
- A subtitle or another audio track is missing: keep the original and check what the output contains. Do not discard a multi-track source based only on successful video playback.
- The output is larger than expected: compare the selected resolution and bitrate with the source. An MP4 conversion does not automatically make every video smaller.
- The player rejects the result: confirm the selected codecs and test the MP4 in the intended player. A different extension alone does not change codecs.
Download All Free Video Converter
Create a new MP4 copy of a local MOV or MKV video.
Frequently asked questions
Which MP4 profile should I start with?
Start with H.264 video and AAC audio, then check the MP4 in the player or device you intend to use. Keep the original resolution and frame rate unless you have a reason to change them.
Does changing the filename to .mp4 convert a video?
No. Renaming a MOV or MKV changes its name, not its container or codecs. Add the source to the converter and create a new MP4 output.
Will conversion keep every subtitle and audio track?
Do not assume that every embedded subtitle or additional audio track is copied to the output. Check the finished file for the sound and subtitles you need before removing the source.
Can I convert multiple videos to separate MP4 files?
Yes. Add the files to the queue, check the MP4 profile for each item and keep Join files off. With joining off, batch conversion creates separate outputs rather than one merged video.