How to Convert AIFF to MP3
AIFF is the lossless PCM container that GarageBand and Logic Pro export by default. The audio is studio-quality; the file size is impractical for sharing — a 3-minute song is 30 MB. Converting to MP3 brings size down 90% while keeping perceptual quality high, since AIFF is the ideal source for any lossy encode. This page is the practical workflow.
Where AIFF Files Come From
Three sources dominate. (1) GarageBand exports: 'Share > Export Song to Disk' offers AIFF, WAV, MP3, and Apple Lossless; selecting AIFF (or 'Audio Interchange File Format') produces uncompressed PCM in an AIFF container at 16-bit / 44.1 kHz by default, optionally 24-bit. (2) Logic Pro bounces: the bounce dialog defaults to AIFF when 'PCM' is selected; common settings are 24-bit / 48 kHz for video work or 24-bit / 44.1 kHz for music releases. (3) Apple sample libraries: many third-party sound libraries ship AIFF samples for hardware samplers (Akai MPC) and historical Mac compatibility. AIFF is identical in fidelity to WAV — same PCM payload, only the byte order differs (big-endian vs little-endian). For conversion purposes, AIFF and WAV are interchangeable. See [what-is-aiff](/guide/what-is-aiff).
Why AIFF Is the Ideal Source for MP3
AIFF is uncompressed PCM — bit-perfect representation of the audio. Encoding from AIFF to MP3 is a single lossy generation: the encoder operates on the cleanest possible input, applies its psychoacoustic model once, and produces a result with minimum artefacts. Compare to encoding from a 256 kbps AAC source to MP3: that's two lossy generations stacked, with cumulative damage. The rule for clean MP3s: encode from lossless. AIFF, WAV, FLAC, and ALAC all qualify. If your AIFF is the master copy of a recording, the MP3 derived from it is the highest-quality MP3 you can make of that audio. Always keep the AIFF master alongside any MP3 derivative — you can re-derive at different bitrates as needs change without quality compounding.
Browser Conversion: Step by Step
Open [AIFF to MP3](/aiff-to-mp3). Drop your .aiff file. The converter decodes the PCM payload and re-encodes as MP3 via WebAssembly ffmpeg locally — no upload. Default output: 192 kbps CBR MP3, source sample rate (44.1 or 48 kHz), source channel count (mono or stereo). Click Download. Speed: 5-10x faster than playback on a 2020-era laptop; a 3-minute AIFF converts in 20-30 seconds. Free tier: 10-second preview. Pro: full files up to 500 MB (sufficient for chapter-length spoken word at 24-bit). For very large session-archive AIFFs over 500 MB, use the ffmpeg path locally.
Bitrate Recommendation: 256-320 kbps for Music
From a lossless source, MP3 bitrate is the only quality knob — and AIFF gives you a clean canvas. Music: 256-320 kbps for archival-quality MP3 from your masters. 192 kbps for a balanced share-with-friends version (essentially transparent on most playback). 128 kbps for quick proof-of-concept previews where size matters more than quality. Voice content (audiobooks bounced from GarageBand, podcast intro/outro): 96-128 kbps mono — speech needs little. ACX audiobook chapters: 192 kbps CBR mono is firm spec; see [audio-for-audiobooks](/guide/audio-for-audiobooks). Demos and rough mixes for client review: 192 kbps stereo is standard. Final delivery to streaming: deliver the AIFF (or its FLAC equivalent) where the platform accepts lossless; otherwise 320 kbps MP3.
ffmpeg One-Liner
Single file: 'ffmpeg -i input.aiff -c:a libmp3lame -b:a 192k output.mp3'. VBR (smaller files at the same quality): '-q:a 2' produces approximately V2 quality, ~190 kbps average. CBR (required by ACX): '-b:a 192k -minrate 192k -maxrate 192k'. Mono: '-ac 1'. Specific sample rate: '-ar 44100'. Combined for ACX submission: 'ffmpeg -i input.aiff -c:a libmp3lame -b:a 192k -minrate 192k -maxrate 192k -ac 1 -ar 44100 output.mp3'. Batch a folder: 'for f in *.aiff; do ffmpeg -i "$f" -c:a libmp3lame -b:a 320k "${f%.aiff}.mp3"; done'. Install ffmpeg via Homebrew on macOS, apt on Linux, static builds on Windows.
GarageBand Direct Export Alternative
If your AIFF originated from GarageBand, you can skip the conversion step entirely. Open the original GarageBand project, choose 'Share > Export Song to Disk', select MP3, choose quality (High = 192 kbps, Highest = 320 kbps), and export. This is a single lossy encode from the project's internal bounce — equivalent quality to converting the AIFF externally. Apple's Core Audio MP3 encoder produces results essentially indistinguishable from LAME's at the same bitrate for typical material. Logic Pro: Bounce dialog > MP3 format option, similar settings. iTunes/Music: import the AIFF, then right-click > Convert > Create MP3 Version (uses the iTunes Plus encoder, default 256 kbps VBR AAC unless you change format). Audacity: import AIFF, File > Export Audio > MP3, set bitrate. Choose whichever fits your workflow.
Edge Cases: 24-bit and High Sample Rate
AIFF supports 24-bit depth and sample rates up to 192 kHz. MP3 has stricter limits: 16-bit only at the encode stage, and sample rates of 8/11.025/12/16/22.05/24/32/44.1/48 kHz only. Conversion handles both automatically: ffmpeg dithers 24-bit down to 16-bit (use '-af 'aresample=osf=s16:dither_method=triangular'' for proper triangular dither), and resamples 88.2/96/176.4/192 kHz down to 44.1 or 48 kHz using a high-quality SOX-based resampler. The 24-bit-to-16-bit dither is essentially inaudible on quiet passages — not a quality concern. The high-sample-rate downsample is handled cleanly by sox/soxr; aliasing is below audible thresholds. AIFF-C (compressed AIFF variant): rare; if encountered, ffprobe shows the inner codec; convert exactly as standard AIFF.