What is AAC?
AAC (Advanced Audio Coding) was developed by a consortium including Fraunhofer (the MP3 inventors), Dolby, Sony, and Nokia, and finalized as an ISO standard in 1997. It was designed as the successor to MP3, addressing the limitations of the older format with a more sophisticated psychoacoustic model, longer transform windows, and better stereo processing. The practical result: AAC achieves the same perceived audio quality as MP3 using roughly 30% less data. A 128 kbps AAC file sounds approximately as good as a 192 kbps MP3. AAC became the codec of choice for Apple (iTunes Store, iPod, iPhone, Apple Music), YouTube (uses AAC for standard quality levels), and most streaming platforms (Spotify uses Ogg Vorbis, but Apple Music uses AAC, YouTube Music uses AAC). AAC is not a file format itself — it's a codec that lives inside container formats: M4A for audio-only files, MP4 for video files with audio tracks, and sometimes AAC files use the raw .aac extension. AAC has several profiles: AAC-LC (Low Complexity, the most common, used in iTunes and streaming), AAC-HE (High Efficiency, used for very low bitrate streaming like internet radio), and AAC-HE v2 (adds Parametric Stereo for even more efficient streaming at very low bitrates). The format is widely supported: all Apple devices, Android (since 2.2), browsers (Chrome, Firefox, Safari, Edge), and most modern hardware players. Older car stereos and some Linux systems may require additional codec support.
AAC pros and cons
Advantages
- 30% more efficient than MP3 — same quality at lower bitrate
- Supported natively by Apple, Android, modern browsers, and most streaming services
- Multiple profiles for different use cases (LC, HE, HEv2)
- Better stereo processing than MP3
- Standard codec for YouTube, Apple Music, and most podcasts
Limitations
- Not as universally supported as MP3 — some car stereos and old devices require MP3
- Multiple profiles can cause confusion about compatibility
- Lossy like MP3 — not suitable for archival use
- Android's AAC support at very low bitrates has historically been poor in some implementations
When should you convert AAC files?
Convert MP3 to AAC when you're creating content for Apple platforms, YouTube, or streaming services where the quality advantage matters at constrained bitrates. Convert AAC to MP3 when you need to play audio on older hardware (car stereos, older speakers) that doesn't support AAC. Convert WAV or FLAC to AAC for high-quality distribution with smaller file sizes than MP3 at the same bitrate.
All FormatDrop conversions run entirely in your browser — no file upload, no server processing. Your files stay on your device.
AAC FAQ
What's the difference between AAC and MP3?
Is Apple Music AAC or lossless?
What audio format does YouTube use?
More formats