Everything runs inside this browser tab. No upload, no sign-up, no watermark — the audio never leaves your computer.
No files yet. Drop one above, then press Convert.
Updated
How to convert M4A to MP3
Drop your M4A files into the box above, or click it to choose them.
Pick a bitrate: 128k suits most audio, 192k and up for music, 96k with Force mono for speech.
Press Convert, then Download. Each MP3 keeps its original name, so my-song.m4a becomes my-song.mp3.
Why convert here
No upload. Conversion happens in your browser; your audio never leaves your device.
No limits. Convert as many files as you like, with no upload limit, no queue and no daily cap.
Works offline once the page has loaded.
Batch conversion with one press of Convert, and Download all when there are several.
MP3 file size by bitrate
The converter writes constant-bitrate MP3, so the size depends only on the bitrate and the length of the recording.
Bitrate
Good for
Per minute
10 minutes
64 kbps
Voice memos
0.46 MB
4.6 MB
96 kbps
Speech and podcasts (with Force mono)
0.69 MB
6.9 MB
128 kbps
Everyday listening
0.92 MB
9.2 MB
192 kbps
Music
1.37 MB
13.7 MB
256 kbps
Music, highest setting offered
1.83 MB
18.3 MB
How it works
Your browser decodes the M4A with its built-in audio decoder, the Web Audio API’s decodeAudioData. lamejs, a JavaScript port of the LAME MP3 encoder, then writes the MP3. Both run inside this tab, which is why the converter keeps working offline and never needs to upload anything.
Yes — free, with no sign-up, no file limit and no watermark. The conversion runs on your own computer.
Are my files uploaded?
No. Your browser decodes the M4A and encodes the MP3 locally; nothing is sent to a server.
Does converting to MP3 lose quality?
M4A (AAC) and MP3 are both lossy formats, so converting re-encodes the audio. At 192 kbps or higher the difference is very hard to hear; for spoken word, 96 kbps mono is plenty and makes much smaller files.
How big will the MP3 be?
About 0.92 MB per minute at 128 kbps, the default. The converter writes constant-bitrate MP3, so size is simply bitrate times length: a 10-minute recording is about 6.9 MB at 96 kbps and 13.7 MB at 192 kbps.
Can I convert several files at once?
Yes. Drop them all in together, press Convert once, then use Download all.
What else can it convert to MP3?
Anything your browser can decode, which usually includes AAC, MP4 audio, WAV, FLAC and OGG.