What happens when you convert MP4 to AAC
- Only the sound is converted; the video is left out.
- Both formats are lossy. Re-encoding loses a little quality, so pick a bitrate at least as high as the original's.
- Mono and stereo are kept (or choose either); surround sound is mixed down to stereo.
- Tags such as title, artist and cover art aren't copied yet.
MP4 vs AAC
| Feature | MP4 | AAC |
|---|---|---|
| Compression | Video file | Lossy |
| Size per minute | — | 1.2 MB |
| Plays on | Almost everything | Most devices and apps |
| Best for | Video | Streaming, mobile |
How to convert MP4 to AAC
- Drop your MP4 files on the box above, or click it to choose files. You can add many at once.
- Adjust the options if you want. The defaults work well for most files.
- Click Download for each AAC file, or "Download all" to get a ZIP.
Frequently asked questions
Is it safe to convert my files here?
Yes. Conversion happens entirely in your browser. Your files are never uploaded to a server, so nobody else can see them.
Is it free? Are there limits?
It's completely free, with no sign-up, watermarks or daily limits. The only limit is your device's memory for very large files.
Can I convert many MP4 files at once?
Yes. Drop as many files as you like; they're converted one after another and you can download them all as a ZIP.
Will converting MP4 to AAC reduce quality?
AAC removes sounds most people can't hear to make the file smaller. At the default bitrate most listeners won't notice a difference; pick a higher bitrate to be safe.
Can I extract the audio from MP4 videos?
Yes. Drop the video and only its sound is converted. The video never leaves your device.
Which bitrate should I choose?
For music, 192 kbps MP3 or 160 kbps AAC sounds near-identical to the original, and Opus sounds great at 128 kbps. For speech and podcasts, 64–96 kbps is plenty.
Are tags and cover art kept?
Not yet. The sound is converted, but title, artist and album art aren't copied.