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AIFF to MP3.
The right way to fill a stick from a lossless library. AIFF is what a serious Rekordbox library is stored in and it is around 10 MB a minute. When a gig needs a stick rather than a laptop, 320 kbps gets you a tenth of the size from a first-generation encode.
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
You are throwing audio away.
The part every other converter leaves out, because it is the part that sometimes says don't.
Permanent. The AIFF is the master and stays the master; the MP3 is the copy that goes in your bag.
MP3 plays on everything — every CDJ, every controller, every laptop, every pool download. That universality is the entire reason to make one. AIFF is the format Rekordbox is happiest with: it analyses fast, it carries proper tags, and every CDJ in service reads it. It is the same audio as WAV in a different wrapper, so it costs nothing to prefer it.
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
Should I put MP3 or AIFF on my USB?+
AIFF if the stick has room, because there is no reason to degrade a file you already own losslessly. MP3 at 320 if it does not — a 64 GB stick holds around 100 hours of AIFF or 400 of MP3, and for most people the deciding factor is how much of the collection they want to carry rather than the sound.
Does converting to MP3 change the BPM or key?+
No. Lossy encoding changes which frequencies are stored, not how fast or in what key the record plays. Rekordbox will re-analyse the new file and should land on the same numbers; if it does not, the disagreement is the analyser being uncertain rather than the conversion having moved anything.
Will I hear the difference in a club?+
From a proper AIFF at 320 kbps, honestly, almost certainly not — a big system is a much less revealing environment than a quiet room with good headphones. Where you would hear it is a low bitrate: at 128 the content stops around 16 kHz and a well-tuned rig makes that obvious.
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 AIFF is decoded, re-written as MP3 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 AIFF and written into the MP3, 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.
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AIFF to WAV · AIFF to FLAC · FLAC to MP3 · WAV to MP3 · M4A to MP3 · Every direction
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