How to convert MP4 to AAC
- 1
Upload your file
Drag and drop a file or click to select one. Keep this page open while the file uploads and converts.
- 2
Convert MP4 to AAC
NexMedia converts MP4 to AAC on its own servers. Processing time depends on the file size and how busy the queue is.
- 3
Download the converted file
When the conversion finishes, the download appears on this page. Your converted file is kept for 2 hours, then deleted.
About MP4
MP4 (MPEG-4 Part 14) is a container format standardised by ISO. It usually holds H.264 or H.265 video with AAC audio, and it can also carry subtitles and chapter markers.
It is the most widely supported video format: phones, browsers, smart TVs and video sites all play it.
The video inside an MP4 is almost always compressed with a lossy codec, so every re-encode loses a little quality.
Convert MP4 to AAC online free, no account required — AAC is the lossy audio codec that succeeded MP3.
Change MP4 to AAC without losing quality — convert MP4 to AAC free in your browser.
Why is my MP4 file so large? MP4 video is already compressed with H.264 or H.265, so a lower bitrate or resolution shrinks the file at the cost of some quality.
About AAC
AAC (Advanced Audio Coding) is the lossy audio codec standardised in MPEG-2 and MPEG-4 as the successor to MP3; at the same bitrate it generally sounds better than MP3.
It is the audio in most MP4 videos, in Apple Music and on YouTube; a .aac file is a bare AAC stream without a container.
A bare .aac stream has only limited room for tags and cover art, so music players usually expect AAC inside an M4A file.
Why convert music to AAC instead of MP3? At the same bitrate AAC sounds better, and every modern phone, computer and streaming service decodes it.
What changes when you convert MP4 to AAC
- The soundtrack of the MP4 is re-encoded as AAC at the default settings, so it is close to the original but not bit-identical.
- Only the sound is kept: the AAC file contains the audio track of your MP4, and the picture is dropped.
Settings you can change
Before you convert MP4 to AAC, you can adjust: Audio codec, Rate control, Audio bitrate, Quality (VBR), Sample rate, Channels, Normalize loudness, Trim start, Trim duration, and Keep tags.
Limits
Each plan sets a maximum file size and a number of conversions per day, and video and audio files also have a maximum length. Guests can convert files up to 100 megabytes and 5 per day; a free account raises this to 500 megabytes and 25 per day; paid plans go up to 100 gigabytes.
Your converted AAC file is kept for 2 hours, then deleted.
MP4 to AAC: questions and answers
Does converting MP4 to AAC reduce quality?
The soundtrack of the MP4 is re-encoded as AAC at the default settings, so it is close to the original but not bit-identical.
What is the difference between MP4 and AAC?
MP4 is a widely supported video container, usually holding H.264 video and AAC audio. AAC is the lossy audio codec that succeeded MP3.
Can I change the settings when converting MP4 to AAC?
Before you convert MP4 to AAC, you can adjust: Audio codec, Rate control, Audio bitrate, Quality (VBR), Sample rate, Channels, Normalize loudness, Trim start, Trim duration, and Keep tags.
Do I need an account to convert MP4 to AAC?
No. You can convert MP4 to AAC without an account; signing in raises the file-size and daily limits.
How long is my converted AAC file kept?
The AAC file you convert from MP4 is kept for 2 hours, then deleted automatically.
When I convert MP4 to AAC, can I keep just the sound?
Only the sound is kept: the AAC file contains the audio track of your MP4, and the picture is dropped.
Will converting MP4 to AAC change my original file?
No. The conversion reads your MP4 and writes a new AAC file, leaving your original MP4 file untouched.