M4A Converter

M4A is the audio file of the Apple world: AAC for everyday music and voice memos, Apple Lossless (ALAC) for exact copies. This converter turns MP3, WAV, FLAC, OGG and other audio into M4A, or M4A into MP3 or WAV, keeping the title, artist, album and cover art. It runs in your browser, so nothing is uploaded.

How to use this tool

1. Choose one or more audio files.
2. Pick M4A (AAC) for small files, M4A (Apple Lossless) for exact copies, or MP3 / WAV to convert M4A to something else.
3. Choose the bitrate for AAC or MP3: 256 kbps is what iTunes uses.
4. Press Calculate and download the files.

Formula

AAC size ≈ bitrate (kbps) × 1000 ÷ 8 × length (s) · ALAC size ≈ 50–70% of the WAV size

AAC and Apple Lossless are encoded by the ffmpeg engine (about 30 MB, downloaded once) with -movflags +faststart, so files start playing before they finish loading. MP3 and WAV outputs from M4A use your browser's own AAC decoder plus LAME or our WAV writer; Apple Lossless sources are decoded by the engine where the browser cannot. Lossy outputs are decoded again and, only if they would clip, lowered just enough.

Example

A 4-minute FLAC of 25 MB becomes an M4A (AAC) of 256,000 ÷ 8 × 240 = 7.7 MB at 256 kbps, or an Apple Lossless M4A of about the same 25 MB that decodes to exactly the same samples.