AIFF → MP3
AIFF to MP3 converter
Uncompressed AIFF audio is re-encoded to MP3. Like WAV → MP3 this is a first-generation lossy encode from a perfect source, and the file becomes roughly 8–11× smaller.
…or drag files and folders here. Add as many as you like — everything is processed on this device.
.aif .aifc .aiff .caf .wav .wave
In one paragraph
AIFF is the Apple equivalent of WAV: big-endian uncompressed PCM with a chunked header. Logic Pro, Pro Tools and older Ableton sessions bounce to it by default, so a producer’s export folder is full of 60 MB files that cannot be emailed or uploaded to a client review tool.
Sonic Batch handles both plain AIFF and the compressed AIFF-C variants that trip up Chrome and Firefox, because the engine decodes them itself instead of relying on the browser. Drop the whole bounce folder in and get MP3s with your track names preserved.
Does this change the audio quality?
First-generation encoding from uncompressed audio, which is the ideal case for MP3. At 320 kbps this is a reasonable reference bounce to send a client; it is still lossy and not a master.
- AIFF can hold 24-bit and 32-bit float samples. MP3 is 16-bit internally, so the extra depth is used during encoding and then gone.
- Sample rates above 48 kHz are resampled, since MP3 stops at 48 kHz. Bounces at 88.2 or 96 kHz are reported per file.
- Loop points and marker chunks that AIFF can carry are not representable in MP3 and are dropped.
A worked example
Sending a client three mix revisions without a file-transfer service
- Drop the three AIFF bounces in. The source panel confirms bit depth and sample rate for each.
- Pick High quality (320 kbps) and leave Channels on “Same as source”.
- Set the Title and Artist fields in the metadata controls so the revisions are labelled in the client’s player.
- Download each MP3 individually — three files do not need a ZIP.
Reference bounces: 320 kbps. Rough demos: 192 kbps.
If the MP3 is going to be judged — a mix approval, a mastering reference, a sync submission — use 320 kbps so codec artefacts are not mistaken for mix problems. For a quick idea sent to a bandmate, 192 kbps is a third of the size and sounds fine on a phone. Never bounce a master to MP3 and then master from the MP3.
Supported formats, limits and browser notes
Sonic Batch decodes with the browser when it can (faster, no engine download) and falls back to the self-hosted WebAssembly engine when it cannot. Every combination below works in every listed browser; the column only tells you which decoder does the work.
| Input | What it is | Chrome | Firefox | Safari | iOS |
|---|---|---|---|---|---|
| AIFF | Apple’s uncompressed PCM format — the WAV equivalent for Logic and Pro Tools. | Partial | Partial | Native | Native |
| WAV | Raw PCM samples with a small header. Perfect fidelity, roughly 10 MB per stereo minute. | Native | Native | Native | Native |
| CAF | Apple container used by older iOS Voice Memos. Usually holds ALAC, IMA4 or raw PCM. | Engine | Engine | Partial | Partial |
| Output | Encoder | Bitrates / depth | Sample rates | Tags |
|---|---|---|---|---|
| MP3 | libmp3lame | 32–320 kbps | 8–48 kHz | Yes + artwork |
- Max per file
- 400.0 MB
- Max per queue
- 4.00 GB
- Max duration
- 4:00:00
- Max archive
- 1.50 GB
These are enforced ceilings, checked before any decoding starts, not measured maximums — a file over the limit is rejected rather than allowed to exhaust the tab’s memory. Real-world capacity is lower on older phones, which is why the scheduler runs one file at a time on iOS and Safari.
Where your audio goes
Nowhere. Your file is read from disk into this browser tab with the File API, decoded and encoded by code running in that same tab, and handed back to you as a download. It is never transmitted.
That is a structural property of the application, not a policy promise: there are no API routes, no server actions and no third-party processing services in this project, so there is nothing capable of receiving a file. The page’s Content-Security-Policy also restricts connections to this origin, and the automated test suite includes a browser test that fails if any network request during import, preview, conversion or download carries media bytes.
The trade-off, stated plainly:results live in your tab’s memory until you download them. Closing or reloading the page discards them. There is nothing on a server to recover, because nothing was ever put there.
Troubleshooting
Chrome says it cannot decode my .aif file.
Chrome fails on AIFF-C with compressed payloads and on some 32-bit float files. Sonic Batch falls back to the WASM engine automatically; you may notice a short delay while the engine loads on the first such file.
The output is 48 kHz rather than 96 kHz.
MP3 has no sample rate above 48 kHz. The resample is done with a proper filter and is listed in the per-file warnings.
My file is 700 MB and will not load.
The per-file budget is 400 MB, which protects your tab from an out-of-memory crash. Bounce a shorter section, or bounce to WAV at 16-bit first to halve the size.
Frequently asked questions
Is AIFF better quality than WAV?
No. Both store the same uncompressed PCM; they differ in byte order and header layout. Converting AIFF to WAV is lossless, and converting either to MP3 costs exactly the same amount.
Will the MP3 be quieter than the AIFF?
Peak level is preserved, but MP3 decoding can produce inter-sample peaks slightly above the original. If your bounce peaks at 0 dBFS, use the normaliser with a −1 dBTP ceiling to avoid clipping on playback.
Can I convert AIFF to something lossless instead?
Yes — AIFF to WAV is a byte-faithful PCM conversion, and FLAC gives you lossless compression at about half the size.
Are my unreleased mixes safe here?
They never leave your device. There is no upload endpoint, no analytics on file contents, and the page’s Content-Security-Policy forbids connections to other origins.