Convert M4A to MP3
Turn iPhone voice memos and Apple Music-era M4A files into MP3s that play anywhere, without uploading them.
- Nothing is uploaded
- Works offline after first use
- Open source
- No sign-up, no watermark. The limit is your device’s memory (phones hold less).
Convert M4A audio, iPhone voice memos and iTunes files, to MP3 in your browser. It is free, needs no account and adds no watermark, and your files are not uploaded: everything runs in your browser on your device. The limit is your device’s memory, which is smaller on a phone, and after your first run the page works offline.
Your iPhone may take a few seconds to prepare the video first, longer if it's stored in iCloud.
Done
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Open the network tab. Your files never appear in it.
Add files and run the tool to see every request this tab makes.
Your files are processed on this device and never sent to a server. Reload the page to clear everything from memory.
M4A is Apple’s name for audio in an MP4 container, normally AAC. It is what the iPhone Voice Memos app saves, what iTunes ripped CDs into, and what many Android recorders and WhatsApp exports produce. It sounds good and files are small, but plenty of things still want an MP3: older car stereos, some podcast and transcription services, school and work upload forms, and audio editors on Windows.
Voice memos are also exactly the kind of recording that should not pass through a stranger’s server: interviews, lectures you recorded, notes to yourself, a doctor’s appointment. This page converts them in your browser. The M4A is decoded by your browser’s own AAC decoder and written as an MP3 by the LAME encoder running in the page.
This page opens at 128 kbps, which is more than enough for speech and still fine for most music. For a voice memo, switch to mono and drop to 96 kbps: the MP3 is a quarter smaller and the voice stays clear. Drop a whole folder of memos and they convert in one go.
Have a different kind of file? The MP3 converter takes any video or audio file.
How it works
- Drop one or more M4A files, or tap to pick them. On an iPhone, share a voice memo to Files first, then pick it here.
- Keep 128 kbps for voice, or raise it to 192 or 256 kbps for music. Choose mono for recordings from one microphone.
- Convert, and the MP3 downloads. Several files download as a zip.
In your browser, not on a server
Your browser decodes the sound track with the same audio decoders it uses to play media on any website (AAC for MP4, MOV and M4A; Opus or Vorbis for WebM; FLAC, WAV and MP3). The samples are resampled to 44.1 kHz and handed to LAME, the reference MP3 encoder, compiled to WebAssembly and served by this site. WAV files are written directly by a few lines of code in the page. A WMA, which no browser plays, is decoded in a background worker by a separately loaded decoder module. Most video runs on your browser's WebCodecs through Mediabunny. For old formats the browser cannot read, the page loads a decoder built from FFmpeg's libraries (LGPL) only when you convert such a file. Everything happens in memory in your tab.
Compared with upload-based tools: Online converters upload the whole video just to keep its sound, cap free files at a few hundred megabytes, and make you wait in a queue. Home videos, lectures and voice memos are personal. Here the file never leaves your device, so a 1 GB video converts as fast as your computer can read it, and the limit is your device’s memory (phones hold less).
Verify it yourself. Give the page a short while after your first run to save itself for offline use, then turn off Wi-Fi or switch to airplane mode and run the tool again. Or open your browser's developer tools (F12, or Cmd-Option-I on a Mac), pick the Network tab, and watch it while you convert. The panel above does the same count for you.
Questions
How do I get a voice memo off my iPhone to convert it?
In Voice Memos, tap the memo, then the three dots, then Save to Files. Open this page in Safari, tap the drop zone and choose the memo from Files. The MP3 lands in your Downloads folder in Files.
Will protected iTunes files convert?
Only files without copy protection. Songs bought from iTunes before 2009 can carry FairPlay DRM (they end in .m4p), which browsers cannot decode. Everything recorded or ripped yourself converts.
Is M4A better quality than MP3?
At the same bitrate, AAC in an M4A usually sounds a little better than MP3. Convert only when something needs an MP3, and pick a bitrate at least as high as the original to avoid an audible drop. To go the other way, see MP3 to AAC.
Is the file uploaded anywhere?
No. There is no server in this process. The page is a static file and the work is done by code running inside your browser tab. Give the page a short while after your first run to save itself for offline use; then you can turn off Wi-Fi and it still works.
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