Audio to AAC Converter

Convert Audio to AAC

AAC (Advanced Audio Coding) is the MPEG codec designed as the direct successor to MP3 — it delivers better sound at the same bitrate and reaches a given quality in a noticeably smaller file. It is the default audio format on iPhones and iPads, in the iTunes and Apple Music catalog, on YouTube, and in most Android and streaming pipelines. This converter takes almost any common audio file and re-encodes it to AAC. One honest caveat up front: AAC is a lossy codec, so the quality you get depends entirely on whether your source is lossless (WAV, FLAC) or already lossy (MP3, OGG) — the sections below explain exactly what to expect. The output here is a raw .aac stream; if you need cover art and tags, see the M4A note further down.

How to Convert Audio to AAC

1. Upload Your Audio File: Drag and drop or click "+ Add Files" to add MP3, WAV, FLAC, OGG, OPUS, M4A, WMA, AIFF, AC3, AMR, or any other accepted audio format. Batch conversion works — drop several files and they encode with the same settings.
2. Set the Bitrate under File Compression: The panel opens on Quality Preset, the hands-off mode — and the least predictable control here, with nothing actually pre-selected in it. Use Variable Bitrate for a size-efficient encode (five AAC bands, 20k-32k up to 96k-112k), Constant Bitrate to lock to a value like 128, 192, or 256 kbps, Custom Bitrate for a precise number, or Specific file size to cap the output in MB.
3. Audio Channel, Sample Rate, Trim (Optional): Switch Audio Channel from Original to Mono to roughly halve the size of voice recordings, lower the Audio Sample Rate (for example 44.1 kHz down to 24 kHz for speech), or open Trim to export only a section by start time and duration.
4. Convert and Download: Click "Convert". Files are uploaded over an encrypted connection, processed on our servers, and the AAC drops into your downloads — no sign-up, no watermark, no software install.

AAC Format at a Glance

AAC vs the Formats You'll Upload

Whether AAC is a size win or just a compatibility change depends on what you start with. This table covers the formats accepted by this converter:

Raw .aac (ADTS) vs AAC in an M4A Container

AAC audio can live in two different wrappers, and the difference matters. This page outputs a raw .aac file — technically an ADTS (Audio Data Transport Stream) that holds only the compressed audio frames. It plays fine, but it cannot store cover art, track titles, artist tags, or chapter markers. The .m4a (and .mp4) container holds the exact same AAC audio but adds a metadata layer for artwork and tags — which is why iTunes, Apple Music, and most music libraries use .m4a. If you want a tagged, album-art-ready file for a media library, convert to the container instead with Convert Audio to M4A; the codec is identical, so there is no extra quality cost.

Popular Audio-to-AAC Conversions

• MP3 to AAC — shrink an existing MP3 library while keeping broad device support
• WAV to AAC — turn an uncompressed master into a small, portable file
• FLAC to AAC — get lossless-sourced audio onto phones that lack a FLAC player
• Audio to MP3 — when a very old car stereo or player predates AAC

Frequently Asked Questions

Which audio formats can I convert to AAC?

The converter accepts the common audio formats — MP3, WAV, FLAC, OGG, OGA, OPUS, M4A, M4B, WMA, AAC, AC3, AIFF, AIF, AIFC, AU, AMR, CAF, WEBA, DSS, and VOC. For a single dedicated route you can also use the per-format pages such as MP3 to AAC, WAV to AAC, or FLAC to AAC.

Is AAC actually better than MP3?

At the same bitrate, generally yes. AAC was designed as the successor to MP3 and uses a more efficient encoder, so it reaches a given quality in roughly 30% smaller files — a 128 kbps AAC file is widely regarded as comparable to a 192 kbps MP3. The gap is widest below 128 kbps and narrows at high bitrates; at 256 kbps and above most listeners cannot tell them apart. MP3's one lasting edge is raw compatibility with very old hardware.

Will converting an MP3 to AAC improve its quality?

No. Both are lossy, so converting MP3 to AAC is a lossy-to-lossy transcode — the detail the MP3 encoder already discarded is gone for good and cannot be restored. Converting can preserve quality if you match or exceed the source bitrate, but it can never add quality back. The real quality win for AAC comes from encoding a lossless source such as WAV or FLAC.

What bitrate should I use for AAC music?

For stereo music, 128 kbps AAC is near-transparent (hard to distinguish from the source) for most listeners, and Apple's iTunes Store ships tracks at 256 kbps for extra headroom. In our testing, a 3-minute 44.1 kHz stereo WAV of about 30 MB encoded to AAC at 256 kbps produced a file of roughly 5.7 MB — about one-fifth the size — with no audible difference on consumer headphones. For voice, podcasts, or audiobooks, 64-96 kbps in mono is plenty.

What's the difference between a .aac file and an .m4a file?

Both contain AAC audio, so they sound identical at the same bitrate. A .aac file is a raw ADTS stream that carries only the audio frames — no cover art, titles, or chapters. An .m4a file wraps that same audio in an MPEG-4 container that can hold metadata and album art, which is why Apple libraries use it. If you need tags and artwork, convert to M4A instead of a raw .aac.

Does AAC play on Android, Windows, and the web, or is it Apple-only?

AAC plays nearly everywhere. Android has decoded AAC since its earliest releases (the raw .aac ADTS stream is officially supported), Windows has built-in AAC playback, and in the browser AAC works in the HTML5 audio element across Chrome, Safari, and Edge, with partial support in Firefox. The "Apple-only" reputation comes from the .m4a container occasionally confusing non-Apple software, not from the AAC codec itself.

My file is already AAC or M4A — should I re-encode it?

Usually no. An .m4a or .aac file already contains AAC audio, and re-encoding it to AAC is another lossy pass that can only lose quality. Only re-convert if you specifically need to change the bitrate, switch to mono, lower the sample rate, or trim the clip. If you simply need a different extension, rewrapping is better than re-encoding.

How do I make the AAC file smaller?

You have several levers. Lower the Constant Bitrate or drop to a lower Variable Bitrate band — those name the size directly, while the Quality Preset dropdown is the hands-off route and the least predictable one here; switch Audio Channel to Mono for voice content to roughly halve the size; reduce the Audio Sample Rate for speech; or use Specific file size to cap the output directly in MB. As a rough guide, 128 kbps stereo AAC is about 1 MB per minute. If you want to shrink a file without changing its format at all, use the Audio Compressor.

How long do my files stay on the server?

Files are uploaded over an encrypted connection, converted on our servers, and then deleted automatically a few hours after conversion. There is no sign-up and no watermark, and your files are never shared or made public.