FLAC to AAC Converter
Compress lossless FLAC files into AAC-LC at the encoder's default bitrate, keeping the original sample rate and channel layout. Note that this page writes a raw .aac (ADTS) stream, which cannot store tags or artwork; pick M4A if you need your metadata to survive.
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Why Convert FLAC to AAC
FLAC is the archival format of choice for ripped CDs and bought downloads because it is bit-exact: decode it and you get the original samples back. The cost is size. A FLAC album runs several hundred megabytes, which is a lot of phone storage for music you listen to on earbuds. AAC was standardized as the successor to MP3 and is the native codec of the Apple ecosystem, Android, YouTube and most car head units, so it is the sensible destination for a listening copy.
The conversion runs on our servers with ffmpeg. The FLAC stream is decoded losslessly, then re-encoded with ffmpeg's built-in AAC-LC encoder at its default rate control, roughly 128 kbps for stereo and around 69 kbps for mono. The result is written as a raw ADTS stream with the .aac extension, not as an MP4 container. There are no settings to adjust: bitrate, profile and sample rate are fixed by the encoder defaults.
What carries over: the sample rate, including unusual rates like 96 kHz, and the channel layout, so a 5.1 FLAC stays 5.1. What is lost: AAC is lossy, so this step throws away audio data permanently and cannot be undone. Raw ADTS has no metadata container at all, so artist, album, title, track numbers and embedded cover art do not survive. Keep your FLAC files as the master copy.
People search for this when they are shrinking a hi-res or CD-rip library for a phone, feeding audio to a tool or device that specifically wants an .aac elementary stream, or preparing a track for software that imports ADTS. If you want the same codec but with your tags and album metadata intact, use our FLAC to M4A page instead: it uses the same AAC encoder inside an MP4 container that stores tags.
How to Convert FLAC to AAC
- Decide between .aac and .m4a first. Both get the same AAC-LC audio from us; only .m4a keeps tags and chapters. If your library depends on artist and album fields, convert to M4A.
- Drop your .flac files onto the upload area or click to browse. Several files can go in at once, and the page also accepts other audio sources such as WAV, ALAC in M4A, APE or AIFF.
- Mind the per-file limit. FLAC albums get large: 50 MB per file as a guest, 100 MB with a free account, 200 MB on Plus and 1 GB on Pro. Single tracks are almost always fine; a whole-album FLAC may not be.
- Start the conversion. Each file is decoded and re-encoded on our servers. Album-length tracks of a few tens of megabytes typically finish in a handful of seconds.
- Download each .aac file. It takes the original base name with the new extension, so the track order of a numbered rip stays readable.
- If a player refuses the raw stream, remux or convert that file to M4A. Some phones and media apps expect AAC inside an MP4 container rather than a bare ADTS file.
What This Converter Does
- Encodes with ffmpeg's native AAC-LC encoder and writes a raw ADTS stream playable by most mobile and desktop players.
- Keeps the source sample rate untouched, with no forced resampling to 44.1 or 48 kHz.
- Keeps the channel layout, so multichannel FLAC files come out multichannel rather than downmixed.
- Handles 24-bit and high sample rate FLAC input: the decoder reads them, then AAC encodes the decoded audio.
- Takes mixed batches, so you can convert FLAC alongside WAV, AIFF or ALAC files in one upload.
- Output files are named after your inputs, which keeps multi-track folders in order.
Video Tutorial
Watch this step-by-step tutorial to learn how to convert FLAC files to AAC format online for free using MiConvert.com. No software installation required.
Frequently Asked Questions
Can I choose 256 kbps, or a VBR quality level?
No. This converter has no quality controls; it uses ffmpeg's AAC-LC default, which lands near 128 kbps for a stereo track. If you need a specific bitrate, encode locally with ffmpeg or a desktop encoder where you can pass the setting yourself.
Is FLAC to AAC lossless?
No, and no conversion to AAC can be. FLAC is lossless, AAC is a lossy codec. The decode step is exact but the encode step discards audio data, so treat the .aac file as a listening copy and keep the FLAC as your master.
Why did my artist, album and cover art disappear?
A raw ADTS .aac file has nowhere to store them. This is a limitation of the format, not a bug. Convert to M4A instead if you want tags preserved; cover art is dropped on every target we produce, so artwork needs to be re-added in a tag editor.
Will the .aac file play in iTunes, on an iPhone, or on Android?
The AAC-LC audio itself is supported everywhere, but some players only accept AAC inside an MP4 container. If a raw .aac file does not appear in your music app, convert that track to M4A, which is the same audio in the container Apple and Android music apps expect.
Can I convert a full FLAC album at once?
You can upload several files in one go, up to 10 as a guest or on a free account, 25 on Plus and 50 on Pro, within 10 conversion jobs per hour per IP for free users. A single very large file, such as a one-file album rip, may exceed your per-file size limit.
What if my FLAC is 24-bit/96 kHz?
It converts fine. The sample rate is kept at 96 kHz in the AAC output. Bit depth is not a property of AAC, so the 24-bit resolution is simply part of what the lossy encode approximates. For a hi-res archive copy, keep the FLAC.
Some FLAC files failed with an invalid data error. Why?
That message means the file was truncated or is not really FLAC inside, which happens with interrupted downloads and renamed files. Re-download it, or play it locally first to confirm it decodes, then try again.
What happens to my files after conversion?
The uploaded FLAC is deleted as soon as the job finishes. The .aac output can be downloaded for roughly four hours, then it is removed automatically. Processing happens on our servers; file names, sizes and outcomes are logged.