Free online AIFF to AAC converter

Many phones, media libraries, and delivery systems accept AAC audio but not large AIFF masters. Converting creates a much smaller playback copy while leaving the original AIFF available for editing and archival use.

What AIFF contains

AIFF (Audio Interchange File Format) is an Apple-developed audio container used primarily for uncompressed PCM recordings. Files normally use .aiff or .aif; stereo 44.1 kHz, 16-bit PCM occupies roughly 10 MB per minute.

AIFF is common in older Mac workflows, studio exchanges, DAW projects, and uncompressed audio exports from software such as Logic Pro, GarageBand, Pro Tools, and Audacity. Standard AIFF is usually PCM, although the related AIFF-C variant can also contain compressed audio.

What AAC provides

AAC (Advanced Audio Coding) is a lossy audio codec that reduces file size substantially compared with uncompressed AIFF. AAC-LC is the usual profile for music and general playback.

AAC is commonly delivered in an MPEG-4 audio container with the .m4a extension. A file ending in .aac is usually a raw AAC stream with ADTS framing, which has weaker metadata and artwork support than .m4a.

For stereo music, use 192 kb/s as a practical default or 256 kb/s for a higher-quality library copy. Speech commonly needs 64–128 kb/s, depending on source quality and required clarity.

Convert the file

Upload the AIFF file to 101convert.com, choose AAC as the output, set a bitrate when that option is available, and download the result. Check whether the receiving program requires an .m4a file or a raw .aac file; choose .m4a unless the device or service explicitly requests AAC/ADTS.

For repeatable local conversion, FFmpeg can create an M4A file with AAC audio:

ffmpeg -i input.aiff -c:a aac -b:a 192k output.m4a

Replace 192k with 256k when needed. To create an ADTS AAC stream for software that specifically requires .aac, use:

ffmpeg -i input.aiff -c:a aac -b:a 192k -f adts output.aac

On macOS, the Music app can convert imported files after setting Music → Settings → Files → Import Settings to AAC Encoder. Add the AIFF file to the library, select it, then use File → Convert → Create AAC Version.

Audacity can export to M4A/AAC when FFmpeg import/export support is installed and enabled. Open the AIFF file, select File → Export Audio, choose M4A (AAC) Files, select the available bitrate or quality setting, and save with an .m4a extension.

Quality and compatibility limits

AAC encoding is lossy. Converting the AAC result back to AIFF cannot restore removed audio data, so retain the AIFF master for editing, mastering, and future encodes.

Keep the source sample rate unless the destination specifies otherwise: retain 44.1 kHz for a 44.1 kHz source and 48 kHz for a 48 kHz source. Upsampling does not add detail, and unnecessary resampling can alter the signal.

Verify album art, track names, and other tags after conversion when they matter, because AIFF metadata does not always map directly to M4A metadata. For multichannel sources, confirm that the destination supports multichannel AAC; otherwise create a controlled stereo downmix before encoding.