Is this AAC to M4A converter really free?

Yes. Up to 5 files at a time, no signup, no catch. The free tier adds a small watermark to image output — Pro ($9.99/mo or $49/yr) removes it, raises the file size limit to 500 MB, and unlocks unlimited batch conversion.

Are my files uploaded to a server?

No — and you can verify it yourself. Open DevTools → Network tab, then convert a file. You'll see zero upload requests. Everything runs right in your browser. We never see your files.

How long does conversion take?

Usually 1–3 seconds for a typical file. The very first conversion on a fresh page load may take 5–20 seconds while the converter engine loads — after that it's instant. Your CPU does all the work locally.

What is the file size limit?

Free: up to 10 MB per file, 5 files per batch. Pro: up to 500 MB per file, unlimited batch. If you're working with large videos or RAW photos, Pro is built for that.

Can I batch convert multiple AAC files at once?

Yes — drop multiple files at once (or Ctrl/Cmd+click to select them) and they all convert in parallel. Free accounts handle up to 5 files per batch; Pro has no limit.

What bitrate will the converted audio use?

We default to 192 kbps for MP3, 128 kbps for OGG/Opus, and 320 kbps for M4A/AAC. These settings are perceptually transparent — most listeners can't tell the difference in a blind test.

Will my metadata (ID3 tags, album art) be preserved?

Yes, when both formats support it. Tags carry over on conversions like MP3→M4A or FLAC→MP3. WAV has limited tag support, so some metadata may not transfer.

Is there any audio quality difference between AAC and M4A?

None — M4A is simply an MP4 container with an AAC audio track. The conversion is a container remux with zero re-encoding, so quality is bit-for-bit identical.

Why does iTunes accept M4A but not AAC?

iTunes was designed around the M4A/MP4 container, which supports rich metadata, album art, and chapter markers. Raw .aac files lack these container features, so iTunes ignores them in favour of .m4a.

How private is this converter?

Completely private — by design, not policy. There is no upload endpoint. Files are processed right inside your browser tab and disappear the moment you close it. We collect only anonymous page-view counts; your file content is never seen or stored.

AAC to M4A Converter — Free, Online, No Upload

How to convert AAC to M4A online

1
Drop your AAC file
Drag and drop your Advanced Audio Coding file onto the converter, or click to browse your files. You can select up to 5 at once. Nothing leaves your device — conversion happens right here in the browser.
2
Hit Convert — it happens locally
Click Convert and watch it go. There's no upload, no server queue, no waiting. The converter runs Advanced Audio Coding → MPEG-4 Audio entirely in your browser tab. Most files finish in 1–3 seconds.
3
Download your M4A
Your MPEG-4 Audio file is ready. Click Download, or grab a ZIP if you converted a batch. Close the tab and everything disappears — no copies kept anywhere.

AAC vs M4A: format overview

AAC

Advanced Audio Coding

Dolby, Fraunhofer, Sony, Nokia · 1997

Compression: lossy
Transparency: No

✓ Successor to MP3 — better quality at same bitrate
✓ Native support across Apple, Android, YouTube
✗ Not fully royalty-free

M4A

MPEG-4 Audio

Apple / MPEG Group · 2001

Compression: lossy
Transparency: No

✓ Better quality than MP3 at same bitrate (AAC codec)
✓ Native Apple ecosystem support

AAC magic bytes: FF F1 (ADTS) / 00 00 00 xx 66 74 79 70

M4A magic bytes: 00 00 00 xx 66 74 79 70 4D 34 41

Why convert AAC to M4A?

AAC and M4A contain identical audio — the difference is the wrapper. A raw .aac file is a bare AAC bitstream; an .m4a file is the same audio tucked inside an MPEG-4 container. The distinction is purely structural, but it has real consequences: iTunes ignores raw .aac files, Apple Music won't import them, and the iOS Music app won't play them. The MP4 container that M4A uses is what enables rich metadata, embedded album art, and the chapter markers that podcasts rely on.

If you have .aac files downloaded from a streaming tool, extracted from a broadcast system, or generated by audio processing software, converting them to M4A is the step that makes them visible and playable in the Apple ecosystem. The process is a container remux — the audio data is extracted from the raw AAC bitstream and wrapped in an MP4 container without any re-encoding. Quality is bit-for-bit identical to the source; file size changes are negligible.

The resulting M4A file will work in iTunes, Apple Music, GarageBand, Logic Pro, QuickTime, and on every iPhone and iPad without any additional software. It will also be accepted by podcast hosting platforms like Buzzsprout, Anchor, and Apple Podcasts Connect. AirPlay, CarPlay, and HomePod playback all work natively with M4A. No quality is lost in the process.

Quality & file size: AAC to M4A

Typical file sizes: AAC 2–5 MB → M4A 3–6 MB.

Both AAC and M4A use lossy compression. We transcode at high quality settings (equivalent to M4A's recommended web quality) to minimize generational loss.

Color depth: AAC supports standard color, M4A supports standard color.

Transparency: AAC does not support transparency. M4A does not support transparency — transparent areas become solid white.

Frequently asked questions

Privacy: how FormatDrop handles your files

Your AACfiles are converted 100% inside your browser. They are never uploaded to our servers, never stored, and never seen by anyone other than you. This isn't a privacy policy claim — it's an architectural guarantee: our server has no endpoint that receives file bytes.