Files never leave your device. Any size, any length.
M4A to MP3.
No size, no length limits.
Voice memos and iTunes-era tracks; MP3 plays on everything, including car stereos.
Files never leave your device. Any size, any length.
Voice memos and iTunes-era tracks; MP3 plays on everything, including car stereos.
Device or cloud
M4A audio files (MPEG-4 audio) usually carry AAC, ALAC audio and come from iPhone Voice Memos, Apple Music purchases, GarageBand. Voice memos and iTunes-era tracks; MP3 plays on everything, including car stereos.
AAC converts on-device; ALAC (Apple Lossless) needs the cloud.
Is my M4A file uploaded?
Usually not — most M4A files convert on your device. AAC converts on-device; ALAC (Apple Lossless) needs the cloud.
Is there a file size or duration limit?
No. mp3fy streams the file while converting, so a 20 GB recording or a 10‑hour lecture works the same as a short clip.
What bitrate should I pick?
192 kbps is the sweet spot for music and speech; 128 kbps for voice notes and podcasts; 320 kbps if you want the maximum. You can also keep stereo or down‑mix to mono.
Are my tags and cover art kept?
Yes — title, artist, album and embedded cover art are carried over into the MP3 when the source has them.