Turn AAC files into FLAC
This makes a FLAC out of the AAC you already have. AAC sounds better than MP3 at the same file size, noticeably so in smaller files. Expect the FLAC to be a good deal bigger, which is what keeping every detail costs. Your file never leaves your computer.
Need the other direction? Convert FLAC to AAC
How to convert AAC to FLAC
- 1 Drop your AAC .aac file onto the page, or click to browse for it.
- 2 Check the options. Nothing is thrown away on the way to FLAC, so there is no quality dial to set.
- 3 Convert. The work happens on your own machine, so how long it takes depends on your computer and the file.
- 4 Download the FLAC, or add more files and do the whole set in one go.
Why convert AAC to FLAC
- You want a copy that will not get any worse each time you edit and save it, and FLAC gives you that.
- Identical to the recording at roughly half the size of a WAV.
- Fast decoding and good tagging with embedded artwork.
- Archiving CD rips without losing anything.
- AAC: opus sounds better in very small files.
AAC compared with FLAC
How the two formats differ on the things that decide whether a conversion is worth making.
| Property | AAC | FLAC |
|---|---|---|
| File extension | .aac | .flac |
| Compression | Lossy | Lossless |
| Typical file size | Smaller | Larger |
| Browser support | Every browser | All current browsers |
| Introduced | 1997 | 2001 |
| Developed by | ISO/IEC MPEG | Xiph.Org Foundation |
Quality and what changes
FLAC stores every pixel exactly, but it can only preserve what the AAC already contained. The compression artefacts baked into the source are preserved perfectly along with everything else, so the picture does not improve, it just stops degrading. Expect the file to grow substantially, often several times over, because AAC was discarding data that FLAC now has to write out in full.
- One FLAC limitation to keep in mind: wasted on speech and on recordings that were never good to begin with.
Questions about AAC to FLAC
Does converting AAC to FLAC improve the quality?
No. FLAC preserves what it is given perfectly, including the compression artefacts already present in the AAC. It stops further loss from happening, which is worth doing before editing, but it cannot recover detail that was discarded.
Why is my FLAC bigger than the AAC?
Because AAC was discarding data and FLAC is not. A lossless format has to write out every pixel it is handed, artefacts included, so growing several times over is normal and does not mean anything went wrong.
Is my AAC file uploaded anywhere?
No. The whole thing runs inside the browser tab you already have open. Your AAC is read straight from your own disk, converted on your machine and handed back as a FLAC. Nothing is sent anywhere, nothing is stored and there is no account.
Is there a file size limit?
There is no server-side limit because no server sees the file. The real ceiling is your device memory, since the input and the output both have to fit in the tab. A few hundred megabytes is usually fine on a desktop machine and considerably less on a phone.
Can I convert several AAC files at once?
Yes. Add as many as you like and they are processed one after another, then offered as separate FLAC downloads or as a single ZIP. Speed depends on your own processor rather than on a queue.
Does the converter work offline?
Yes, after the page has loaded once. The engine is cached by the browser, so you can disconnect, reload and keep converting. That falls out of doing the work locally rather than being a separate mode you switch on.