M4A to MP3 Converter
Convert an M4A file to MP3 in your browser. M4A is the default format for iPhone voice memos, GarageBand exports, and most iTunes downloads — but it's not as universally accepted as MP3. This page handles the conversion locally; your audio never uploads.
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Stays on your device
Your audio is decoded into your browser's memory by the Web Audio API, re-encoded by a JavaScript library running in the same tab, and the result goes straight to your downloads. No upload, no log, no third party. Sensitive recordings, voice memos, copyrighted tracks — none of it leaves your machine.
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M4A → MP3 done right
M4A is a container around the AAC codec — high quality, smaller than MP3, but not playable in every app. MP3 plays literally everywhere. The output is encoded at 192 kbps by default (near-CD quality); pick a higher or lower bitrate if you need to.
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Quality control
Pick the MP3 bitrate that matches your use case — 128 kbps for podcasts and voice (smaller files), 192 kbps for music (our default, near-CD quality), or 320 kbps for archival (best fidelity, largest files).
Frequently asked questions
Does my audio ever leave my device?
No. The conversion runs entirely in your browser. We decode your file using the Web Audio API and re-encode it using a JavaScript encoder library, all in your browser tab. Open DevTools while you convert — you'll see zero traffic carrying your audio.
Is there a file size limit?
No fixed limit from us. The real ceiling is your device's memory: decoded audio sits in RAM as raw PCM, which is roughly 10 MB per minute of stereo audio at 44.1 kHz. A typical 5-minute song needs about 50 MB of working memory — fine on any modern phone or laptop. Hour-long podcasts may struggle on older devices.
Will the conversion change the audio quality?
MP3 is a lossy format, so encoding to MP3 always involves some quality loss compared to the source. At 192 kbps (our default), the difference is inaudible to most listeners on most playback hardware. WAV is lossless — if you're converting TO WAV, the output is bit-identical to what your source decoded into. If you're converting FROM a lossy source (MP3, M4A), the WAV won't be higher quality than the source — it'll just be uncompressed.
How long does conversion take?
Decoding is near-instant. Encoding speed depends on output format: WAV is essentially instant (just writing bytes). MP3 takes about 1 second of compute per 10 seconds of audio on a modern laptop — so a 5-minute song encodes in roughly 30 seconds. Phones are slower; expect 2-3x longer. Progress is shown live as the encoder works.
Does this work on mobile?
Yes. Tap the drop zone to open the file picker, choose your audio file, hit Convert. The result downloads to your device's standard download location. iOS users: the file lands in the Files app under Downloads.
What about ID3 tags (artist, album, song title)?
Original ID3 tags are not preserved in v1 — the encoded file gets no metadata. The audio itself is preserved exactly. If you need to keep artist/album/title info, you'll want to re-tag the output with a tool like MP3Tag (Windows) or Kid3 (cross-platform) after converting.
What's the difference between M4A and MP3?
M4A is a container holding AAC-encoded audio. AAC is a more modern codec than MP3 — better quality per kilobyte. But MP3 is older and universally supported, so it's the safer choice for sharing, uploading, or playing on older devices and software. If your goal is portability, MP3 wins.
Will the MP3 sound worse than the M4A?
Technically, slightly. M4A at the same bitrate as MP3 sounds a bit cleaner because AAC is a more efficient codec. But at 192 kbps (our default), the difference is below the threshold of audibility for most listeners on most playback hardware. If you have the original lossless source (WAV/FLAC), encoding from THAT to MP3 gives marginally better quality than going M4A → MP3 — but again, the difference is subtle.
Will it work on iPhone voice memos?
Yes. iPhone voice memos export as M4A by default. Drop one in here and you'll get an MP3 you can upload anywhere — Google Docs, email, transcription services, podcast hosts that only accept MP3.
Does the conversion preserve length and quality?
Length is preserved exactly. Quality depends on the bitrate you pick: 320 kbps gives the highest fidelity (recommended for music), 192 kbps is great for most uses (our default), 128 kbps is fine for voice and podcasts and produces smaller files.