Step 1: Supply your AAC files using the button above or by haul and lay.
Step 2: Click the 'Convert' button to start the conversion.
Step 3: Get your converted FLAC files.
AAC to FLAC Conversion FAQ
What does the AAC to FLAC audio converter do?
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AAC is already lossy, so converting to FLAC preserves the existing audio without further degradation, but it cannot recover detail lost in the original encode. FLAC is right if you plan to edit and resave without compounding compression artifacts.
Will the FLAC file be much larger than the source AAC?
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Yes — lossless audio is typically 5-10x larger than lossy audio at perceptually equivalent quality. Plan for ~10 MB per minute for FLAC versus ~1 MB per minute for high-bitrate AAC.
Does converting AAC to FLAC improve the audio quality?
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No, and it is worth being blunt: nothing can. The AAC already discarded detail during its original encode, and wrapping what remains in a lossless FLAC preserves exactly that — no more. The file gets several times larger and sounds identical. It is still the right move before editing, because FLAC will not add a second generation of artefacts when you export. FLAC gives you WAV fidelity at half the size, with proper metadata tags and embedded artwork, which is why it dominates lossless music libraries. AAC is patent-encumbered, and a handful of very old players still refuse it where they would accept an MP3.
What exactly is a FLAC file?
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A container with the audio inside it, rather than the audio on its own. That extra layer is where the length, the seek index and whatever metadata the format defines are kept, so a player knows how long a FLAC is before decoding a single frame instead of scanning the whole file to find out. It also means the extension does not always settle what is inside: several containers of this kind are allowed to hold more than one sort of audio, which is why two FLAC files can behave differently while looking identical from outside. FLAC uses linear prediction plus Rice coding to reach roughly 50-60% of the original size while decoding back to bit-identical PCM.
Why did my phone or tablet record in AAC?
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Because it is what the hardware encoder on the device produces. Voice memos, screen recordings and the audio track of anything filmed on a phone come out as AAC without anyone choosing it, which is why so many files arrive in it and why the quality is usually better than the file size suggests. Nothing about that stops it converting; it just means the source was encoded once already, by a chip optimised for battery life rather than for fidelity. AAC is Advanced Audio Coding, standardised in 1997 as MPEG-2 Part 7 and designed explicitly to replace MP3.
Will the FLAC play in my car or on older hardware?
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Often not. AAC is decoded by essentially everything, including car head units and elderly players; FLAC needs software that knows the codec, which standalone hardware frequently does not have. If the destination is a car stereo or a portable player, that is a strong argument for staying on AAC. FLAC is still several times larger than a good lossy file, and Apple’s ecosystem only added support recently and grudgingly.
Is there a licence attached to AAC?
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Not one you have to think about. The codec is covered by patent pools, and the licensing is settled by whoever ships the decoder — the phone, the browser, the operating system — long before a file reaches you. It is why the format is everywhere in hardware, and why royalty-free alternatives were built at all. It changes nothing about converting a file you already have, and it is only a live question if you are shipping an encoder yourself.
Is there a file-size limit when converting AAC to FLAC?
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Free conversions have a size limit per file, set by the type of file, and the page tells you when a file is over it. A paid plan removes that limit, so much larger files can be converted.
Can I batch-convert several AAC files to FLAC at once?
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Several files in one job need a paid plan. Free use is one file per conversion, one conversion an hour. On a paid plan you can add several files to one job, then download each result on its own or all of them in one ZIP.
What happens to my AAC files after the conversion?
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Uploaded files are processed on our own conversion servers, nobody looks at them, and they are not shared. The upload and the converted file are both deleted automatically about 24 hours after the conversion, which leaves time to download the result. See /privacy/ for the full policy.
What apps can play a FLAC file?
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FLAC plays in most music players, browsers, and media libraries. iTunes / Apple Music, VLC, Foobar2000, and phone media apps handle it natively.
Do I need to install software to convert AAC to FLAC?
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No. The converter runs entirely in your browser plus our cloud — no plugin, no install, no admin rights. It works on Windows, macOS, Linux, ChromeOS, iOS, and Android.
