Unuploaded

Converter · No upload

M4A to MP3, without uploading anything

Drop in M4A or AAC audio — voice memos, recordings, music you own — and download MP3s that play on anything. The conversion runs entirely inside your browser: nothing is uploaded, and the network meter below proves it live.

Statusidle Files— File— Duration— Sample rate— Channels— Bitrate192 kbps Output size— Network since file read—

How this converter works

When you choose a file, the browser's File API hands this page the bytes in memory — no transfer happens, because the file is already on your machine. Your browser then decodes the M4A itself: AAC decoding is built into every current browser, so this site ships no decoder at all for your files. The raw audio samples are re-encoded to MP3 at the bitrate you chose by lamejs, a JavaScript port of the LAME encoder (LGPL), running inside this tab, and the result is handed back as a download link. A server never appears in the pipeline because this site doesn't have one.

The encoder is the one thing that downloads, once — before any file of yours is read, so the network meter's zero is honest. After it lands you can run the strongest check yourself: switch your wifi off entirely and convert. It still works, because nothing in the conversion ever wanted a connection. A tool quietly shipping your recordings elsewhere could not survive that test. The methodology page covers the other two ways to verify, and publishes the encoder's license and provenance.

The honest limits: M4A to MP3 is a lossy-to-lossy re-encode, so the MP3 can only lose a little relative to the M4A, never gain — keep the original. The bitrate dial decides the trade: 128 kbps is compact and fine for speech, 192 kbps (the default) is near-transparent for most music, 320 kbps is the ceiling of the format. Tags and album art are not carried across, because only the decoded audio is re-encoded. DRM-protected purchases can't be decoded and are reported as errors rather than silently skipped, and unusual sample rates or multichannel audio are remixed by the browser's own resampler into what MP3 can hold.

Frequently asked questions

Is my audio uploaded anywhere?
No. Your browser opens the file with its File API, decodes the M4A's audio itself, and a JavaScript MP3 encoder running inside this tab re-encodes it — all in memory, on your device. The readout's network meter counts every request from the moment your file is read and stays at zero, and the methodology page shows how to verify that independently.
Will converting M4A to MP3 lose quality?
Slightly, and unavoidably: M4A and MP3 are both lossy formats, so this is a lossy-to-lossy re-encode. The MP3 inherits whatever the M4A already discarded and adds a small generation of its own. At 192 kbps and above the difference is inaudible to most people on most material, but keep the M4A as your original — converting back won't recover anything.
What bitrate should I choose?
192 kbps, the default, is a sensible trade for music — roughly 1.4 MB per minute and transparent or near it for most listeners. Choose 128 kbps for voice recordings and lectures where small files matter more than fidelity, and 320 kbps when you want the most the MP3 format can hold. A higher bitrate never restores what the M4A already lost; it only preserves more of what's still there.
Do my tags and album art survive the conversion?
No. This tool decodes the audio to raw samples and re-encodes those samples, so the container's metadata — title, artist, album art — is not carried across. The sound is everything that survives. If your library depends on tags, plan to re-tag the MP3s in your player afterwards.
Why won't a particular file convert?
The usual culprits are DRM protection and damage. Old protected music-store purchases (often .m4p, sometimes renamed) are encrypted, and no converter can legally or technically read them in a browser. A truncated download or corrupt file also fails to decode. Either way the file gets its own error row naming the problem — nothing is silently skipped — and the other files in your batch still convert.

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