Online AAC Audio Compressor
Shrink AAC files — the codec behind YouTube, Spotify, and Apple Music
AAC (Advanced Audio Coding) is the modern successor to MP3 and the dominant codec for streaming audio. It powers YouTube, Spotify, Apple Music, and virtually every podcast feed. At the same bitrate, AAC delivers noticeably better audio quality than MP3, especially below 128 kbps. Our free AAC compressor re-encodes your raw AAC (ADTS) files at a lower bitrate while preserving the codec's superior efficiency. Processing is entirely browser-based — files never touch a server.
What You Can Do
- Reduce AAC file size by 30–80% depending on target bitrate
- Six quality presets from Maximum (256 kbps) to Minimum (48 kbps)
- Custom bitrate slider for precise control over file size
- Downsample to 22 kHz or 16 kHz for speech-only content
- Convert stereo to mono for podcasts and voice memos
- All processing in-browser — zero server uploads, complete privacy
How to Compress an AAC File
- Upload your AAC file by dragging it to the page or clicking the browse button
- Select a quality preset or move the custom bitrate slider to your target
- Optionally adjust sample rate and channels under Advanced settings
- Click Compress and download the smaller AAC file
Frequently Asked Questions
What is the difference between AAC and M4A?
AAC is the codec (compression algorithm), while M4A is an MPEG-4 container that usually contains AAC audio. A raw .aac file uses the ADTS container, which is a simpler framing format without metadata support. Our AAC compressor works with raw .aac (ADTS) files specifically. For M4A files, use our M4A compressor.
Is AAC better than MP3?
Yes, at the same bitrate AAC produces audibly better quality than MP3. This advantage is most pronounced at lower bitrates (64–128 kbps), where AAC maintains clarity while MP3 introduces noticeable artifacts. This is why streaming platforms chose AAC over MP3.
What is the best bitrate for AAC streaming?
128 kbps AAC is considered transparent quality for most listeners and is the standard for music streaming on Spotify (normal quality) and YouTube. 96 kbps AAC is roughly equivalent to 128 kbps MP3. For podcasts, 64 kbps mono AAC provides excellent speech clarity.
Why do streaming platforms use AAC?
AAC offers better compression efficiency than MP3, meaning higher quality at lower bitrates. It supports features like SBR (Spectral Band Replication) for enhanced low-bitrate performance. It is also part of the MPEG-4 standard, ensuring broad device and browser support.
Can I convert AAC to MP3 instead of compressing?
Converting a lossy format to another lossy format (AAC to MP3) causes generational quality loss — both codecs discard different parts of the audio. It is better to compress within the same codec. If you need MP3, start from a lossless source like WAV or FLAC.
