Convert MP3 to FLAC MPEG Audio Layer III ↔ Free Lossless Audio Codec Free Online Secure
Your MP3 is decoded here in your browser and written out as FLAC, which stores sound without discarding any of it. What was already discarded, though, stays discarded.
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Where these formats come from
MP3 came out of years of research at Fraunhofer and was standardised in 1993 as part of MPEG-1. Its trick is psychoacoustic: it throws away the sound a human ear is unlikely to notice, mostly quiet detail masked by louder sound nearby, and it was that trick which made music small enough to travel over a modem. AAC — the thing inside an .m4a file — was designed as its successor and does the same job better at the same size. Ogg Vorbis appeared in 2000 as the patent-free answer, at a time when MP3 still had to be licensed. FLAC compresses without discarding anything, giving back the identical recording at about half the size, and WAV stores the raw samples with no compression at all.
Where you meet them
MP3 is still the format that plays on anything with a speaker, which is why it is the safe choice for sending something to a stranger. M4A is what Apple devices and most phones record and buy in. OGG travels inside games and open-source software. FLAC is for archiving a collection or ripping a CD when the original quality must be kept. WAV is the working format of recording and editing, where the file is opened and saved repeatedly and compression artefacts would accumulate.
Questions people ask
Will converting my MP3 to FLAC restore the quality?
No. FLAC will preserve perfectly whatever it is given, but what it is given here is already an MP3 — the detail removed when the MP3 was made is gone, and no later format can invent it back. You end up with a file several times larger that sounds exactly like the MP3. Converting to a lossless format is worth doing only from a lossless source; from an MP3, the honest answer is to keep the MP3.
Each time I convert, does it sound worse?
Between lossy formats, yes — a little. MP3, AAC and Vorbis each decide separately what the ear will not miss, and each conversion decodes the previous guess and makes a fresh one on top of it, so the losses accumulate. Converting once rarely matters; converting back and forth repeatedly does. Lossless formats have no such problem: WAV to FLAC to WAV returns exactly the samples you started with.
Does the file lose quality?
It depends on what the two formats can hold. Converting between formats that store the same thing — a PNG to a BMP, a WAV to a FLAC — loses nothing. Converting into a format that throws information away to save space, such as JPEG or MP3, loses a little every time, and converting back does not bring it back. Where a choice exists, this page errs towards keeping the original quality rather than making the smallest file.
Is my file uploaded anywhere?
No. The conversion happens inside your browser, on your own machine; the file never leaves it and there is no server here that could receive it. That is why a large file is limited by your own memory rather than by an upload, and why nothing you convert can appear in anybody's logs — including ours. The audio and video tools do fetch their conversion engine from this site the first time you use them, some thirty megabytes once; after that the work still happens entirely on your machine.
Why people convert MP3 to FLAC
FLAC is the format of careful listeners. It stores sound without discarding any of it: a FLAC file can be unpacked back into exactly the audio that went in, bit for bit. That makes it the favourite of people who keep music collections for the long term, who edit recordings, or who own equipment that they would like to feed with the best material available. MP3 is the opposite kind of format, built to be small and to leave out whatever the ear is least likely to miss. So it is natural to wonder what happens when you convert MP3 to FLAC, and the honest answer is that it depends on what you expect.
Here is the short version. Converting MP3 to FLAC does not bring back the sound that the MP3 threw away. That sound is gone. What it does is take everything the MP3 still holds and store it from now on without further loss. If a program, a player or a library you are building insists on FLAC, the conversion is the way to get there. If you hope it will improve the sound, it will not.
This page converts MP3 to FLAC in your browser. Your audio is not uploaded anywhere, which matters for voices, interviews and unpublished work. Below you will find how the conversion works, what it keeps, what it cannot do, and the situations in which it makes sense.
How the conversion works
Decoded in your browser, stored as FLAC
Your MP3 is opened inside your browser and decoded back into raw sound, and that sound is then written out as FLAC. Nothing is sent to a server, so there is nothing to delete afterwards. You drop the file, press the button and download the result. There is no bitrate to choose, because FLAC does not discard anything and so has no quality setting to trade against size.
Why the file gets so much bigger
An MP3 is small because it is lossy. A FLAC is large because it keeps every detail of the decoded sound, including the faint artefacts left by the MP3 compression. As a result, a FLAC made from an MP3 is commonly four or five times the size of the MP3. This surprises many people, who expect a file made from a small one to be small too. It is not wasted space in the sense of an error; it is the price of storing the signal in full.
What lossless really means
Lossless means that nothing is thrown away from the sound you give to FLAC. It does not mean that the sound was perfect before. When the starting point is an MP3, the signal already lacks parts, and FLAC preserves that signal faithfully, flaws included.
What is kept
Everything the MP3 still holds
When you convert MP3 to FLAC here, everything the MP3 still holds is stored from now on without further loss. If you later convert the FLAC to another format, or edit it, you start from a clean copy of the decoded sound and not from yet another round of lossy compression.
Length, sample rate and channels
The full length, the sample rate and both channels are kept. A stereo MP3 comes out as stereo FLAC, and the sound is not shortened, sped up or squeezed into one speaker.
A file that opens in every current player
The FLAC file opens in every current player and editor: desktop programs, Android phones, most hi-fi network players, open-source tools and many car systems. A few Apple programs have been slow to support it in the past, so check the destination if it is unusual.
What you should know before you convert MP3 to FLAC
This does not undo the compression
This is the most important thing on the page. What the MP3 threw away is gone, and FLAC simply stores what is left, without throwing away any more, at four or five times the size. Convert MP3 to FLAC when something needs FLAC, and not to improve the sound, which it cannot do. If an offer promises better audio from a converted MP3, be sceptical: no honest converter can restore information that no longer exists.
Titles, artist names and cover art
Titles, artist names and cover art are not carried over. The new file contains the sound and little else. If the tags matter, add them again in a music program afterwards, or keep the MP3 beside the FLAC so that the information is not lost.
The converter is fetched the first time
The converter is not part of the page itself. It is fetched the first time you use one of these audio pages, about nine megabytes, once. After that it stays in your browser, and later conversions start straight away. On a slow connection the first use takes longer.
How to convert MP3 to FLAC here
Add your recording
Drop the MP3 onto the page or pick it from your device. It is read inside your browser and is not uploaded.
Convert
Press the button. A long recording takes a little while, and the page works on your own device, so leave it open until it finishes.
Download and check
Download the FLAC, play it from the beginning, check a passage in the middle and the end and make sure the length matches the original. Note the size: it will be several times that of the MP3.
A closer look at MP3 and FLAC
Where the two formats come from
MP3 appeared in the early nineties, when disks were small and connections slow, and it solved a real problem: music fitted into a few megabytes. FLAC arrived later, in the early 2000s, as a free format that compresses sound without loss, typically to about half the size of the raw recording. It became the standard of enthusiasts who wanted to keep their discs exactly as they were, with the freedom to turn them into anything else later.
Why you rarely gain quality going this way
The usual direction is from lossless to lossy: a FLAC or a WAV becomes an MP3 for the phone. That step makes sense because the lossy copy is small and the lossless one stays in the archive. The opposite direction, as when you convert MP3 to FLAC, does not recover the lost material, so it is mainly a matter of format and not of quality.
Lossy and lossless in a sentence
A lossy format throws information away to save space and cannot get it back. A lossless format keeps everything it is given. If what it is given is already lossy, it keeps that, and nothing more.
When this conversion is worth doing
Software or hardware that only takes FLAC
Some players, network streamers, mastering tools and archive systems accept FLAC and refuse MP3. If your recording exists only as an MP3, converting it is the only way in. The sound will be exactly as good as the MP3, no worse and no better.
A clean starting point for editing
When you want to edit a recording, cut it, apply effects and save it several times, it is better to work on an uncompressed or losslessly compressed copy, so that each save does not add another round of loss. If you only have an MP3, you can convert MP3 to FLAC first and edit the FLAC. The editing then stays lossless, and you make a final lossy file only at the very end.
A uniform archive
Some archivists prefer a single lossless format for everything, so that nothing in the collection will be compressed again by accident. Converting your MP3 files to FLAC places them in that archive. Mark them clearly, perhaps in the file name, as having been made from MP3 sources, so that nobody mistakes them for rips from the original discs.
When it is not worth doing
If you simply want a library that sounds better, skip it. If space on your phone is limited, skip it as well, since the files will be much bigger. And if your player already plays MP3, there is nothing to gain.
Questions people ask before converting
Will the sound improve?
No. The FLAC will sound the same as the MP3. It cannot restore what the MP3 discarded.
Why is the FLAC so much bigger?
Because FLAC stores the decoded sound in full, without discarding anything. Four or five times the size is normal.
Can I tell it came from an MP3?
Yes, with the right tools. An analysis of the frequencies shows the cut-off typical of MP3 compression. That is why it is honest to label such files properly.
Will the titles and artist names remain?
No. Titles, artist names and cover art are not carried over.
Is my recording uploaded?
No. The conversion runs in your browser and the recording never leaves your device.
Can I go back from FLAC to MP3?
Yes. FLAC to MP3 makes a small file again, though this is another round of lossy compression.
Choosing wisely when you convert MP3 to FLAC
Think about why you need it
Before you convert MP3 to FLAC, name the reason. A program that demands it is a good reason. A vague feeling that lossless is better is not, because here it will not be better. Knowing your reason keeps you from filling a disk with large files that do nothing for you.
Check your storage
A folder of MP3 files turns into a folder several times larger. Make sure there is room, and think about whether you really need the whole collection converted or only the pieces that cause trouble.
Test one file first
Convert one recording, load it into the player or tool that needs it and make sure it works. If it does, repeat for the others.
Keep the originals
Whenever you convert MP3 to FLAC, keep the MP3. It carries the tags, takes little room and is the file that plays everywhere.
Tips for a tidy lossless collection
Name the files by their source
If you convert MP3 to FLAC for an archive, add a short note to the file name or the folder, such as from-mp3. In a year you will not remember which files came from discs and which from downloads, and the note keeps your collection honest.
Do not convert twice
A FLAC can be unpacked to the same sound as many times as you like, which makes it a safe master. Do not go from FLAC back to MP3 and again to FLAC. The extra round trip adds loss and gains nothing, so make one clean conversion and work from there.
Check what your player supports
Before you convert MP3 to FLAC for a whole library, try one file in the player you use most. Some portable players and older car systems ignore FLAC, and finding out after hundreds of files are converted is an unpleasant surprise.
Privacy and handling
Why local conversion matters for audio
Audio files often hold voices, and voices are personal: an interview, a meeting, a message from a relative, a lesson. Many online converters upload your file to a server, process it and send it back, and for a while a copy lives on a machine you do not control. Here your own browser does the work, and the recording stays on your device.
What happens when you leave
When you close the page, the converted file disappears from the browser, so download it first. The converter, about nine megabytes, stays in your browser storage so that the next conversion starts faster. Your recordings are never kept.
If something goes wrong
The page freezes with a very long recording
Everything happens on your device, and a FLAC of several hours is large. A phone may run out of memory. Try again on a computer, or split the recording into shorter parts first.
The FLAC does not play on a device
Try another player first. Some older devices and some Apple software do not read FLAC. In that case an MP3 to M4A conversion or the original MP3 will serve you better.
The file is far too large
That is how lossless storage behaves. If size matters more than anything else, the MP3 was already the right format, and you can leave the conversion undone.
Related audio conversions
The audio tools of this site cover the other common pairings. To make small files from lossless ones, use FLAC to MP3 or WAV to MP3. For uncompressed sound that editing programs like, MP3 to WAV is the nearest relative of this page. If what you need is another lossy format, MP3 to OGG and MP3 to M4A do the job, and OGG to MP3 and M4A to MP3 go the other way.
A worked example
Say you are preparing a recording of a local choir for an archive that accepts only FLAC. Your only copy is an MP3 of 8 megabytes. You drop it here and press the button. A few seconds later you download a FLAC of about 36 megabytes with the same length and both channels. It sounds exactly like the MP3 did, and it is accepted by the archive. You note in the description that the source was an MP3, and you keep the original file in your own records.
A short checklist
Before converting
Check that something really needs FLAC. Make sure there is room for larger files. Keep the MP3 safe.
While converting
Stay on the page until the file is ready. Do not start other heavy tasks on a phone.
After converting
Download the FLAC, listen to the beginning and the end, and label it so that its origin is clear.
Common mistakes
Expecting better sound
Do not convert MP3 to FLAC hoping to hear a difference. There will be none.
Deleting the MP3 to save space
The MP3 is the small copy. The FLAC is the large one. Deleting the small one to make room defeats the purpose.
Passing off the result as a true lossless rip
A FLAC made from an MP3 is not equal to one ripped from a disc. Label it honestly so that nobody is misled.
Your recording stays on your device
The conversion happens locally. Your recording is read by your own browser, converted there and handed back. Nothing is uploaded, so no copy ends up on a server and nobody else can listen to it. For voices and private recordings, that is the safe way to convert MP3 to FLAC.
Summary
To convert MP3 to FLAC here, drop the file and press the button. Your MP3 is decoded in your browser and written out as FLAC, which stores sound without discarding any of it. What was already discarded stays discarded: everything the MP3 still holds is stored from now on without further loss, at four or five times the size. The full length, the sample rate and both channels are kept, and the file opens in every current player and editor. Convert to FLAC when something needs FLAC, not to improve the sound. Titles, artist names and cover art are not carried over. The converter is fetched the first time, about nine megabytes, once. Nothing leaves your device.