MP3 to FLAC Converter
FileFlip converts MP3 to FLAC entirely inside your browser, using WebCodecs and FFmpeg compiled to WebAssembly. The file is never uploaded to a server: it is read off your disk, converted on your own machine, and saved back by the browser. That means no file-size limit, no queue and no account.
How do I convert an MP3 file to FLAC?#
- Drop your MP3 file onto the converter at the top of this page, or click it to pick one from your computer. You can add as many as you like.
- Leave the target set to FLAC and the conversion starts on its own. FileFlip usually downloads nothing, falling back to 30.8 MB of WebAssembly if your browser cannot encode these codecs itself, then runs WebCodecs and FFmpeg on your own machine.
- Save the FLAC file. Your browser writes it straight to your downloads folder, because there was never a server holding it.
Does converting MP3 to FLAC lose quality?#
Sometimes. When the codecs inside the MP3 file are ones the FLAC container can hold, the streams are copied straight across and nothing at all is lost. When they are not, the file has to be decoded and encoded again, and that step does cost a little quality.
Is it safe to convert MP3 files online?#
Yes, because nothing is uploaded. FileFlip converts MP3 files inside the browser tab you already have open, using WebAssembly builds of the same engines a desktop converter would install. Your file is read from your own disk into the page's memory, and no request carrying it is ever made.
You do not have to take that on trust. Open your browser's network panel, run a conversion, and you will see the engine come down and your file go nowhere. There is no upload, no server-side copy, no retention window, and no account tied to what you converted.
How FileFlip works lists every engine, its version and its download size, and shows how to check for yourself that nothing leaves your machine.
What MP3 to FLAC actually does to the file#
Converting MP3 to FLAC runs on WebCodecs and FFmpeg, usually downloads nothing, falling back to 30.8 MB of WebAssembly if your browser cannot encode these codecs itself, copies the streams through when the codecs fit and re-encodes when they do not.
| Engine | WebCodecs and FFmpeg |
|---|---|
| Conversion path | One step: MP3 → FLAC |
| Downloaded to your browser | Nothing in most browsers, or 30.8 MB if yours cannot encode these codecs itself |
| Quality | Lossless when the codecs fit, lossy when they do not |
| You get back | One file |
| Where it runs | In a background worker, so the page stays responsive |
What survives the conversion
| What is in the file | This conversion | Why |
|---|---|---|
| Encoded streams | Sometimes | Survives for some files and not others. |
Worth knowing before you start:
- whether the browser can do this without FFmpeg depends on the codecs it exposes through WebCodecs
- the encoded streams are copied when the file's codecs fit the target container, and re-encoded when they do not
What is an MP3 file?#
An MP3 file stores audio encoded with MPEG-1 or MPEG-2 Audio Layer III, a lossy codec that permanently discards sound it predicts a listener won't notice in order to shrink the file to roughly a tenth the size of the original PCM recording.
Pick MP3 when a file needs to play anywhere without a second thought about compatibility.
Convert MP3 to an uncompressed format like WAV only when a downstream tool requires PCM input, keeping in mind that the conversion cannot restore audio the original encoding already discarded.
What is a FLAC file?#
A FLAC file holds audio compressed with the Free Lossless Audio Codec, which shrinks the data by roughly 40-60% and reconstructs the exact original samples, bit for bit, on decode.
Use FLAC to archive or edit audio when you want compression without giving up any of the source quality.
Convert FLAC to MP3 or AAC for a portable device or streaming use case where storage space matters more than keeping a bit-perfect copy.
MP3 to FLAC questions people ask#
Does converting MP3 to FLAC improve the sound quality?
No, converting an MP3 to FLAC does not improve its sound quality. FLAC is lossless, but it can only preserve the audio it's given, and by the time a file is an MP3 the compression has already discarded data permanently. Wrapping it in FLAC afterward just produces a larger file that sounds exactly like the MP3.
Is MP3 still patented?
No, MP3 is no longer patented. The key US patent, 6,009,399, expired on April 16, 2017, and Technicolor, which administered MP3 licensing on Fraunhofer's behalf, wound the licensing program down shortly after. European patents on the format had already expired by 2012.
What plays MP3 files?
Nearly everything plays MP3 files: Windows Media Player and VLC on Windows, Music and QuickTime Player on macOS, the built-in players on iOS and Android, and every modern web browser through the HTML5 audio element. It's the one audio format that never needs a compatibility check.
Does converting MP3 to AAC or another lossy format lose quality?
Yes, converting an MP3 to AAC or any other lossy format loses additional quality. Each lossy codec introduces its own compression artifacts, and decoding an MP3 back to PCM and re-encoding it as AAC stacks the new artifacts on top of the ones already baked in, an effect audio engineers call generation loss.