Is my audio file uploaded anywhere?

No. The tool reads only the filename and file size using the browser File API. No audio data ever leaves your device. The FFmpeg command is generated entirely in your browser.

What is the difference between M4A and AAC?

M4A is a file container (MPEG-4 Audio) that holds AAC-encoded audio. The audio codec inside an M4A file is AAC. Renaming an .m4a file to .aac is usually harmless, but M4A is the standard extension used by iTunes, Apple Music, and iOS.

AIFF (Audio Interchange File Format) is an uncompressed audio format developed by Apple. It stores CD-quality or higher audio without any quality loss, but results in very large file sizes — typically 10 MB per minute at 16-bit/44.1 kHz stereo.

Which bitrate should I choose for M4A?

96 kbps is suitable for voice recordings and podcasts. 128 kbps is the standard for general music listening. 192 kbps offers high quality. 256 kbps is Apple Music's default and is recommended when archiving music you care about.

How accurate is the estimated M4A file size?

The estimate uses the formula: (bitrate_kbps / 8) * duration_seconds * 1024 bytes, plus a small container overhead. The actual size may differ slightly based on encoder efficiency and metadata, but the estimate is accurate to within 5–10%.

Can I convert AIFF to M4A without FFmpeg?

Yes. In iTunes or Apple Music on macOS/Windows, go to File > Convert > Create AAC Version after setting the import format to AAC in preferences — the output file will have an .m4a extension. Audacity can also export to M4A if the FFmpeg library is installed.

Does converting AIFF to M4A lose quality?

Yes. M4A/AAC is a lossy format, so some audio information is discarded. At 256 kbps the difference is inaudible for most listeners, but the original AIFF remains lossless. Always keep your AIFF originals if you need lossless copies.

How do I convert multiple AIFF files at once?

Use the batch loop shown on this page. On Linux/macOS: for f in *.aiff; do ffmpeg -i "$f" -codec:a aac -b:a 128k "${f%.aiff}.m4a"; done. On Windows CMD: for %f in (*.aiff) do ffmpeg -i "%f" -codec:a aac -b:a 128k "%~nf.m4a"

AIFF to M4A Converter

Name: AIFF to M4A Converter
Availability: InStock
Author: Nham Vu

Drop an AIFF file to inspect its size and estimate the converted M4A output size, then copy the FFmpeg command to convert it.

Drop your AIFF file here, or browse

.aiff and .aif files — nothing is uploaded

Conversion Options

Output Bitrate

96 kbps (voice / podcasts) 128 kbps (standard music) 192 kbps (high quality) 256 kbps (Apple Music / archival)

Output Filename

Or Type a Filename Manually

Use this if you already know the filename and do not want to select a file.

FFmpeg Command

ffmpeg -i "input.aiff" -codec:a aac -b:a 128k "output.m4a"

Batch Convert (Linux / macOS)

for f in *.aiff; do
  ffmpeg -i "$f" -codec:a aac -b:a 128k "${f%.aiff}.m4a"
done

Batch Convert (Windows CMD)

for %f in (*.aiff) do ffmpeg -i "%f" -codec:a aac -b:a 128k "%~nf.m4a"

About AIFF and M4A

AIFF Uncompressed Apple format. Lossless, very large files. Common in GarageBand, Logic Pro, and Pro Tools on macOS.

M4A MPEG-4 Audio container holding AAC-encoded audio. Lossy, small files. The default format for iTunes purchases, Apple Music, and iOS.

Converting AIFF to M4A is a one-way lossy process. Keep your AIFF originals if you need lossless copies later.

Alternative Conversion Methods

iTunes / Apple Music Go to Preferences > Files > Import Settings, choose AAC Encoder, then right-click your AIFF file and select "Create AAC Version." Output is saved as .m4a.
Audacity Open the AIFF file, then go to File > Export > Export Audio, choose "M4A (AAC)" format. Requires the optional FFmpeg library for Audacity.
FFmpeg (CLI) Use the command generated above. FFmpeg is free and available at ffmpeg.org for Windows, macOS, and Linux.

Summary