How to use the MP4 to AAC converter
- Choose your MP4 video or drop it on the box.
- Pick an audio quality. 192 kbps is the usual choice; 320 kbps for music you care about, 128 kbps for speech.
- Click "Convert to AAC". A progress meter shows how far along it is.
- Download your AAC and listen to it right on the page.
Why convert MP4 to AAC?
A raw .aac file is the audio stream of an MP4 on its own, which some broadcast tools, game engines and hardware players ask for specifically.
- MP4: usually lossy, so quality drops a little each time it is re-encoded.
- AAC: better quality than MP3 at the same bitrate.
If you just want a song for your phone, M4A or MP3 is usually easier to manage than a raw AAC file.
MP4 vs AAC
| MP4 | AAC | |
|---|---|---|
| Full name | MPEG-4 Part 14 | Advanced Audio Coding |
| Type | Video | Audio |
| Created by | Moving Picture Experts Group (MPEG) (2001) | Moving Picture Experts Group (MPEG) (1997) |
| Compression | Lossy | Lossy |
| Typical codecs | H.264 + AAC | AAC |
| Best for | Sharing videos online, phone recordings, social media uploads and streaming | Streaming, video soundtracks and some phone recordings |
| Plays on | Windows, macOS, iPhone, Android, smart TVs, game consoles and every modern browser | Most phones, iTunes and VLC; some players skip raw .aac files |
Does converting MP4 to AAC lose quality?
Only the sound is kept and re-encoded as AAC. Video soundtracks are usually AAC at 128–256 kbps, so choosing 192 kbps or more keeps the AAC sounding the same as the video.
How long does it take?
Fast. Only the sound is decoded, so even a long video usually converts in well under a minute.
What is an MP4 file?
MP4 is a container that usually holds H.264 or H.265 video with AAC sound. It is built on Apple's QuickTime file structure and became an ISO standard in 2001. Because almost every phone, browser, TV and editing app can play it, MP4 is the safest choice when you need a video to just work.
What is an AAC file?
AAC is the successor to MP3 and the sound inside most MP4 videos, YouTube and Apple Music. A .aac file is a raw AAC stream (ADTS) without the MP4 wrapper, which some apps and players handle less well than M4A.
Frequently asked questions
Is the MP4 to AAC converter free?
Yes, completely free, with no sign-up and no watermark. Files up to 1 GB each can be converted, and there is no daily limit.
Are my files safe?
Yes. Files are converted locally in your browser and are never uploaded. When you close the page, nothing is left behind.
Will the AAC sound as good as the MP4?
Only the sound is kept and re-encoded as AAC. Video soundtracks are usually AAC at 128–256 kbps, so choosing 192 kbps or more keeps the AAC sounding the same as the video.
Can I convert AAC back to MP4?
Yes, use the MP4 Converter and choose MP4 as the output.
An MP4 plays without sound. What should I do?
The audio may use a codec your player does not support (for example AC3). Convert it to MP4 again so the sound becomes AAC.
Can I use it on my phone?
Yes. Open the page in your phone's browser and choose a file. Phones have less memory than computers, so very large files are better converted on a laptop or desktop.