AAC-LC, HE-AAC & AAC Profiles Explained
AAC isn't one thing — it's a family of profiles tuned for different bitrates and uses. Here's what AAC-LC, HE-AAC, and HE-AAC v2 mean, and which one you're actually using.
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Convert AAC files →AAC is a family, not a single codec
When people say "AAC," they usually mean one specific profile: AAC-LC. But the AAC standard defines several profiles, each tuned for a different balance of quality, bitrate, and complexity. Knowing which is which explains why a 64 kbps radio stream and a 256 kbps iTunes track can both be "AAC" and sound very different.
| Profile | Full name | Added technology | Best for |
|---|---|---|---|
| AAC-LC | Low Complexity | — (baseline) | The standard: iTunes, Apple Music, YouTube, most apps |
| HE-AAC | High Efficiency | SBR (Spectral Band Replication) | Low-bitrate streaming and digital radio |
| HE-AAC v2 | High Efficiency v2 | SBR + PS (Parametric Stereo) | Very low bitrates; voice and mobile |
AAC-LC (Low Complexity)
AAC-LC is the workhorse. It's what almost every music file uses — iTunes purchases, Apple Music downloads, YouTube audio, and the output of most encoders. "Low complexity" refers to the decoding effort, not the quality: AAC-LC delivers excellent, transparent sound at 256 kbps and is efficient enough to run on any modern device. When a file is described simply as "AAC," it's AAC-LC.
HE-AAC (High Efficiency)
HE-AAC adds Spectral Band Replication (SBR) — a clever technique that reconstructs high frequencies from a compact set of instructions instead of encoding them fully. That lets it sound good at much lower bitrates (roughly 32–64 kbps), which is why it's used for internet radio, low-bandwidth streaming, and digital broadcasting. At those bitrates it clearly beats plain AAC-LC; at high bitrates the two converge and AAC-LC is preferred.
HE-AAC v2
HE-AAC v2 goes further with Parametric Stereo (PS), encoding the stereo image as a small side channel. This squeezes listenable stereo into extremely low bitrates (as low as ~24 kbps), useful for voice, mobile streaming, and constrained broadcast. The trade-off is that it's optimized for efficiency, not audiophile fidelity.
How to tell which profile a file uses
Most desktop players and tools (VLC's Media Information, ffprobe, MediaInfo) show the exact profile. For music you downloaded or purchased, it's almost certainly AAC-LC. HE-AAC and HE-AAC v2 mostly appear in streaming and broadcast, not in files you keep.
Encoders
The profile is chosen by the encoder. Common AAC encoders include Apple's AAC encoder (widely regarded as excellent for AAC-LC), Fraunhofer FDK-AAC (used in many tools, strong HE-AAC support), and FFmpeg's native AAC encoder. For everyday conversion you don't need to pick one — a good tool defaults to high-quality AAC-LC.
Converting AAC files
Whatever the profile, if you need a file that plays on everything, convert to MP3 with our AAC to MP3 converter. New to the format? Start with What is AAC? Comparing AAC to other codecs? See AAC vs MP3 and AAC vs Opus.
AAC-LC, HE-AAC, or anything else — convert it to a universal MP3 free. No account, no software, no limits.
Convert AAC files →Frequently Asked Questions
What is AAC-LC?
AAC-LC (Low Complexity) is the standard, most common AAC profile — used by iTunes, Apple Music, YouTube, and most apps. When a file is labeled just "AAC," it's almost always AAC-LC.
What's the difference between AAC-LC and HE-AAC?
HE-AAC adds Spectral Band Replication to sound good at low bitrates (streaming, radio). AAC-LC is preferred at normal and high bitrates. At 256 kbps you'd use AAC-LC.
Is HE-AAC better than AAC-LC?
Only at low bitrates. HE-AAC wins around 32–64 kbps; at higher bitrates the two converge and AAC-LC is the standard choice.
Which AAC profile does iTunes use?
AAC-LC, typically at 256 kbps — the profile behind iTunes and Apple Music audio.