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MP3 to WAV.
Right before an edit. Pointless as an upgrade. You need uncompressed audio to edit, sample or run through anything that will not open an MP3 — and that is a real, everyday reason to do this. The conversion decodes the MP3 exactly as a player would and writes the result out at full size.
Drop tracks to convert
WAV, AIFF, FLAC, MP3 or M4A. Drop a whole folder’s worth — one set of settings is applied to all of them and they come back as a single archive. Nothing is uploaded; the page makes no network request.
What it costs
A bigger file is not a better one.
The part every other converter leaves out, because it is the part that sometimes says don't.
Roughly ten times the disk, for exactly the audio you already had. Nothing is recovered. If somebody has told you converting to WAV improves an MP3, they were wrong, and the frequency ceiling of the file is the proof — it stays exactly where the encoder left it.
The one thing WAV is bad at is metadata. Its tagging was bolted on late and support is patchy, so artist and title can survive a trip through one program and vanish in the next. AIFF holds the same audio and tags properly, which is why it is the better lossless choice for a library.
The four that matter
What each format is for
Ogg and Opus are missing on purpose: no CDJ reads either, so neither belongs in a DJ's library.
| Format | Size, roughly | What it is for |
|---|---|---|
| WAV | 10 MB a minute | Uncompressed and universal. Opens in everything ever written. Poor at holding tags, which is the one reason to prefer AIFF. |
| AIFF | 10 MB a minute | The same audio as WAV in a container that tags properly. What Rekordbox is happiest with and what every CDJ in service reads. |
| FLAC | About two-thirds of WAV | Lossless compression — identical samples, a third less disk, and a checksum so the file can prove it years later. Read by Rekordbox and the CDJ-3000, but not by the CDJ-2000NXS2. |
| MP3 | About 2.4 MB a minute at 320 | Lossy, permanent, and universal. The right last step for a stick and the wrong middle step in any chain. |
The rule underneath all of it: lossless to lossless costs nothing and can be undone, lossless to lossy costs audio you cannot get back, and lossy to lossless costs disk and recovers nothing. Only the middle one is a real decision.
Frequently asked
Common questions
Does converting MP3 to WAV improve quality?+
No. It is the single most persistent myth in this area, and it is easy to check: an MP3 at 128 kbps has nothing above about 16 kHz, and the WAV made from it has nothing above about 16 kHz either. The container changed and the audio did not. The one thing you do gain is an uncompressed file to edit without stacking another generation of loss.
When should I do this?+
Before editing, sampling, or feeding a track to something that will not read MP3 — and in that case it is exactly right, because every save of an edited MP3 costs another generation. Do not do it to "upgrade" a library; you will spend ten times the disk on the same audio.
Can I tell what the MP3 was originally?+
Partly, and this tool shows you: when it converts it reports the frequency at which the file stops carrying content, which is the fingerprint the encoder leaves. A ceiling around 16 kHz is a 128 kbps file, around 19-20 kHz is 320, and content all the way to the top is what a genuinely lossless recording looks like.
Do my files get uploaded anywhere?+
No, and that is the main reason to use this rather than a site that asks you to wait for an upload. The MP3 is decoded, re-written as WAV and handed back entirely inside this browser tab — open the network panel and watch it stay empty. There is no server behind the page, which means an unreleased promo is safe to drop on it and nothing is sitting in somebody's bucket afterwards.
Can I convert a whole folder at once?+
Yes. Drop as many files as you like, set the format once, and the whole queue is converted with a report for each file — what it came from, what it went to, and how the size compares. The results come back as a single archive rather than as thirty separate downloads, which is what you want when the next step is dragging a folder into Rekordbox.
Do the tags come across?+
Yes. Artist, title, album, album artist, genre, year, track number, label, remixer, composer, BPM, key, ISRC, comment and the cover art are all read off the MP3 and written into the WAV, so a converted folder arrives in Rekordbox named rather than as a wall of filenames. The one thing that does not travel is anything a DJ program keeps in its own private frames — Serato's cue points and beat grid live in an undocumented block that nothing outside Serato reads, and no converter can carry them.
Is there a file size limit?+
Up to 800 MB per file, which is about 75 minutes of 24-bit stereo audio — a full recorded set fits comfortably. Past that it is the browser's own decoder that gives up rather than the tool.
How does this tool make its FLAC and MP3 files?+
The lossless formats are written here, and verified: every test file was decoded again by an independent decoder and compared sample by sample against the original, with zero differences. On real records the FLAC comes out at about 67% of the uncompressed size, which sits between the standard encoder's default setting and its slowest one. MP3 uses the reference encoder that has been the answer to that problem for twenty-five years, because a homemade one would not make bigger files, it would make worse-sounding ones.
Other conversions
MP3 to AIFF · FLAC to WAV · AIFF to WAV · M4A to WAV · Every direction
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DJ terms on this page: FLAC · Lossy compression · Bit rate · WAV and AIFF · Sample rate · Lossless · CDJ · Full glossary