Browser edition: files stay on your device. Up to 100 MB total and 10 minutes. First use downloads a 32 MB engine. Some formats depend on codec support. Public-link downloading is not ready on this free deployment.
Convert MP3 to AAC
Convert MP3 to AAC online for free. Real conversion, batch support, no sign-up.
How to convert MP3 to AAC
- Add your fileDrop it on the page, choose it from your device, or paste it with Ctrl+V.
- ConvertAdjust settings if you like, then press the button. You'll see live progress.
- Browser processing uses original files on your device. Public-link downloading is unavailable.
What happens to your file
MP3 files are common for music libraries, podcasts, car stereos, any device, but not every app or device opens them. AAC is ideal for streaming, video soundtracks, mobile audio. Spool converts MP3 to AAC with FFmpeg — real decoding and encoding, not a renamed file extension.
Lossy → lossy. Converting between compressed formats re-encodes the audio. Pick a bitrate equal to or above the source to avoid audible loss — re-encoding a 128 kbps file at 320 kbps won't make it sound better, but it won't make it worse either.
Settings
- Audio bitrate — 320 kbps · best, 256 kbps, 192 kbps · standard, 128 kbps · small, 96 kbps, 64 kbps · voice
- Channels — Original, Mono
- Sample rate — Original, 48 kHz, 44.1 kHz, 22 kHz
MP3 vs AAC
| MP3 | AAC | |
|---|---|---|
| Full name | MPEG-1 Audio Layer III | Advanced Audio Coding |
| Created by | Fraunhofer IIS / MPEG, 1993 | MPEG, 1997 |
| Type | Lossy audio | Lossy audio |
| Typical contents | MP3 (lossy) | AAC (lossy), raw ADTS stream |
| Best for | music libraries, podcasts, car stereos, any device | streaming, video soundtracks, mobile audio |
| Strength | Universal compatibility | Higher quality than MP3 at equal bitrate |
| Weakness | Lossy: some detail is discarded | Raw .aac files have weaker tag support than M4A |
About MP3
- Type
- MPEG-1 Audio Layer III
- Contains
- MP3 (lossy)
- Use
- music libraries, podcasts, car stereos, any device
About AAC
- Type
- Advanced Audio Coding
- Contains
- AAC (lossy), raw ADTS stream
- Use
- streaming, video soundtracks, mobile audio
FAQ
What bitrate should I choose for AAC?
192 kbps is a good default for music. Choose 320 kbps for the best quality, 128 kbps for podcasts and voice, 64 kbps for small voice notes.
Can I convert several MP3 files at once?
Yes. Drop up to 10 files at a time — each one is converted in parallel and you can download them individually or all at once.
Is there a file size limit?
Convert and edit files on your device. The browser edition accepts up to 100 MB total, media up to 10 minutes and video up to 4K. Codec availability and device memory can limit individual jobs.
Is this MP3 to AAC converter free and safe?
Yes. There are no pop-ups, redirects or fake download buttons, and no software to install. Files are transferred over HTTPS, processed in isolated job folders and deleted automatically.