How to convert m4a to mp3 — free, browser-based, no upload
- Step 1Drop your M4A file — Drag an
.m4a(or.aac) file onto the dropzone, or click to browse. The tool also accepts MP3, WAV, FLAC, OGG, Opus and video as input, but it always outputs MP3. - Step 2Pick a bitrate — Open the Bitrate dropdown — the only control on this tool. Options are 320 kbps (best), 256, 192 (default), 128 (podcast), and 64 (voice). The MP3 is written with LAME at the constant bitrate you choose; there is no sample-rate or channel control here, so the source's sample rate and channel layout pass straight through.
- Step 3Run the conversion in your browser — Processing happens locally through FFmpeg compiled to WebAssembly — the file is never uploaded. The page decodes the AAC audio, re-encodes it to MP3, and copies your tags and any embedded cover art across (ID3v2.3).
- Step 4Download the MP3 — Save the result. Filename keeps the original base name with a
.mp3extension. Title, artist, album and artwork ride along where the source had them, so the file is ready for car stereos, podcast hosts, DAWs, and legacy players. - Step 5Edit tags afterwards if needed — If the M4A had missing or wrong tags, fix them on the MP3 with the ID3 tag editor, or pull the cover art out separately with the album-art extractor.
- Step 6Batch many files on a paid plan — The Free tier converts one file per run. Pro raises that to 10 files (and 200 MB / 120 minutes each); Pro + Media and Developer go to 100 files with no duration cap.
Bitrate options in the picker
The Bitrate dropdown is the only control on this tool. MP3 is encoded with LAME (libmp3lame) at the constant bitrate (CBR) you choose; the default is 192 kbps. There is no sample-rate or channel control here — the source's sample rate and channel layout pass through unchanged.
| Picker value | FFmpeg flag | Typical use | Approx. size / minute (stereo) |
|---|---|---|---|
| 320 kbps · best | -b:a 320k | Music, mastered exports, the highest MP3 quality available here | ~2.4 MB |
| 256 kbps | -b:a 256k | Music and interviews where you want headroom but a smaller file than 320 | ~1.9 MB |
| 192 kbps · default | -b:a 192k | All-round default — transparent for most spoken-word and casual music | ~1.4 MB |
| 128 kbps · podcast | -b:a 128k | Podcasts and talk content where file size matters more than music fidelity | ~0.94 MB |
| 64 kbps · voice | -b:a 64k | Mono voice notes, dictation, transcription source where size is critical | ~0.47 MB |
What is preserved vs. changed in the transcode
The converter runs -c:a libmp3lame -b:a <bitrate> -map_metadata 0 -map 0:a -map 0:v? -c:v copy -disposition:v:0 attached_pic -id3v2_version 3. Tags and embedded artwork are carried across; the audio itself is re-encoded.
| Property | Behaviour | Why |
|---|---|---|
| Title / artist / album / year tags | Copied to the MP3 (ID3v2.3) | -map_metadata 0 carries container metadata; -id3v2_version 3 writes the most widely-read ID3 flavour |
| Embedded cover art | Re-attached, not re-encoded | -map 0:v? picks up the attached picture and -c:v copy copies it byte-for-byte, then marks it attached_pic |
| Sample rate (e.g. 44.1 / 48 kHz) | Passed through unchanged | No -ar flag is set for this tool |
| Channels (mono / stereo) | Passed through unchanged | No -ac flag is set for this tool |
| Audio fidelity | Re-encoded (lossy → lossy) | AAC is decoded then LAME re-encodes to MP3 — a second lossy generation |
Per-file limits by plan
Limits come straight from the audio tier table. Note the per-file DURATION cap is separate from the file-size cap — a long-but-small recording can hit the minutes limit before the megabytes limit. M4A to MP3 is on the Free tier.
| Plan | Max file size | Max duration / file | Files per run |
|---|---|---|---|
| Free | 50 MB | 30 minutes | 1 |
| Pro | 200 MB | 120 minutes | 10 |
| Pro + Media | 100 GB | Unlimited | 100 |
| Developer | 100 GB | Unlimited | 100 |
Cookbook
Concrete before/after conversions. The command blocks show the effective FFmpeg call the in-browser engine runs for each choice — you don't type these, the tool builds them from the Bitrate dropdown.
Default 192 kbps conversion
The out-of-the-box behaviour: drop the file, hit convert, get a 192 kbps MP3 with tags intact. Good enough to be transparent for most spoken-word and casual listening.
Input: interview.m4a (AAC, 44.1 kHz stereo, 9.8 MB)
Picker: 192 kbps · default
Effective command:
ffmpeg -i interview.m4a -c:a libmp3lame -b:a 192k \
-map_metadata 0 -map 0:a -map 0:v? -c:v copy \
-disposition:v:0 attached_pic -id3v2_version 3 interview.mp3
Output: interview.mp3 (192 kbps CBR, 44.1 kHz stereo, ~6.9 MB)
title/artist tags + cover art preservedMusic at 320 kbps to minimise transcode loss
M4A is already lossy, so converting to MP3 adds a second generation. For music you care about, pick the highest bitrate (320) to keep the loss inaudible to most ears.
Input: album-track.m4a (256 kbps AAC, 44.1 kHz stereo)
Picker: 320 kbps · best
ffmpeg -i album-track.m4a -c:a libmp3lame -b:a 320k ... album-track.mp3
Output: album-track.mp3 (320 kbps CBR)
Note: bigger file than the source, because 320k MP3 needs more
bits than 256k AAC to encode the same audio transparently.Voice note shrunk to 64 kbps
A mono dictation or memo doesn't need music-grade bitrate. The 64 kbps voice preset makes a tiny file that's still perfectly intelligible for transcription or email.
Input: meeting-note.m4a (mono, 22 min, 12 MB) Picker: 64 kbps · voice ffmpeg -i meeting-note.m4a -c:a libmp3lame -b:a 64k ... meeting-note.mp3 Output: meeting-note.mp3 (64 kbps, mono preserved, ~10 MB) Tip: channels pass through, so a mono source stays mono.
Converting an .aac file (same codec, different wrapper)
Raw .aac and .m4a carry the same AAC codec — M4A just wraps it in an MP4 container. This tool decodes either and outputs MP3, so there's no separate AAC tool to hunt for.
Input: voicemail.aac (raw AAC stream) Picker: 128 kbps · podcast ffmpeg -i voicemail.aac -c:a libmp3lame -b:a 128k ... voicemail.mp3 Output: voicemail.mp3 (128 kbps) — same conversion path as .m4a; the engine detects the codec, not the extension.
Hand the MP3 to another JAD tool
Conversion is one step in a pipeline. After producing the MP3 you can fix tags, trim it, or size it for chat — each is a separate single-purpose tool.
1. m4a-to-mp3 → podcast-ep.mp3 (192 kbps) 2. /audio-tools/silence-stripper → cut the dead air 3. /audio-tools/loudness-normalizer→ EBU R128 to -16 LUFS 4. /audio-tools/id3-editor → set show + episode tags Each tool runs locally and takes the previous tool's output as its input — nothing is uploaded between steps.
Edge cases and what actually happens
DRM-protected iTunes purchase (.m4p or FairPlay)
Fails — DRMPre-2009 iTunes Store purchases used FairPlay DRM (often a .m4p extension). The browser's FFmpeg cannot decrypt them, so the conversion fails. DRM-free files — 'iTunes Plus' purchases from 2009 onward, voice memos, GarageBand exports, AirDrop'd recordings — convert fine. Apple Music streaming downloads are also DRM-protected and won't convert.
File over the plan's size or duration limit
RejectedFree allows 50 MB and 30 minutes per file. The duration cap is separate from the size cap, so a long mono recording can be under 50 MB yet over 30 minutes — it's still rejected. Pro lifts this to 200 MB / 120 minutes; Pro + Media and Developer remove the duration cap entirely (100 GB).
ALAC (Apple Lossless) inside an .m4a
SupportedSome .m4a files contain ALAC (lossless) rather than AAC. FFmpeg decodes ALAC fine and re-encodes to MP3, so it converts — but you're going from lossless to lossy MP3, so use 320 kbps to preserve as much quality as possible, or keep the ALAC and convert only a copy.
Source M4A has no tags or cover art
By designIf the input has no metadata, there's nothing to copy, so the MP3 comes out with empty tags — not an error. Add title/artist/album afterwards with the ID3 tag editor.
Bigger output file than the source
ExpectedA 256 kbps AAC re-encoded to 320 kbps MP3 will usually be larger, because MP3 is a less efficient codec and 320k packs more bits per second. If small files matter more than fidelity, drop to 128 or 64 kbps, or use the bitrate changer for a target size.
Truncated or partially-downloaded M4A
ErrorAn incomplete MP4 may be missing its moov atom (the index FFmpeg needs), causing a decode error. Re-export or re-download the file in full. A few stalled-download M4As can still play in QuickTime but fail to transcode — the playable bytes aren't enough for FFmpeg to seek.
Variable-bitrate AAC source
SupportedVBR AAC decodes normally; the MP3 output is constant-bitrate at whatever you picked. Don't expect the MP3 to match the source's average bitrate — the picker sets the MP3 rate directly.
Wrong extension on the file
SupportedThe engine detects the actual codec, not the extension, so an .m4a that's really an MP3, or an MP3 mislabelled .aac, still converts to MP3. If a file truly isn't a recognised audio stream, FFmpeg returns a decode error.
Multiple files dropped on the Free tier
LimitedFree processes one file per run. To batch-convert a folder of M4As, upgrade to Pro (10 per run) or higher (100), or convert them one at a time.
Frequently asked questions
Is this M4A to MP3 converter really free?
Yes. M4A to MP3 is a Free-tier tool with no account required — a 50 MB / 30-minute file, one at a time. Paid plans only matter if you need bigger files, longer recordings, or batches.
Does my file get uploaded to a server?
No. The conversion runs entirely in your browser through FFmpeg compiled to WebAssembly. The audio never leaves your device, and once the page has loaded the engine it works offline.
What bitrate should I choose?
192 kbps (the default) is transparent for most spoken-word and casual music. For music you care about, pick 256 or 320. For podcasts pick 128, and for plain voice notes 64 keeps files tiny. The dropdown is the only setting on this tool.
Will converting M4A to MP3 lose quality?
A little — both are lossy, so this is a second generation of compression. Use the highest bitrate (320) to make the loss inaudible for most listeners, and keep the original M4A if you'll need to re-export later.
Does it keep my title, artist, and album tags?
Yes. The converter copies container metadata to ID3v2.3 (-map_metadata 0), so title/artist/album/year ride along when the source has them. If you need to edit tags, use the ID3 tag editor afterward.
Is the album cover art preserved?
Yes — embedded artwork is re-attached and copied byte-for-byte, not re-encoded. If the source had no art, the MP3 simply comes out without it.
Can I change the sample rate or make it mono?
Not on this tool — it only exposes a Bitrate control and passes the source's sample rate and channels through unchanged. For sample-rate changes use the sample-rate converter; to fold stereo to mono is a separate step.
Can it convert .aac files too?
Yes. Raw .aac and .m4a carry the same AAC codec, so this one tool handles both — there's no separate AAC converter to find.
Why won't my iTunes purchase convert?
If it's a pre-2009 FairPlay-DRM purchase (often .m4p) or an Apple Music download, it's encrypted and the browser engine can't decode it. DRM-free 'iTunes Plus' files and your own recordings convert fine.
What's the difference between M4A and MP3?
M4A is AAC audio in an MP4 container — Apple's default. AAC is more efficient than MP3 at the same bitrate, but MP3 plays on far more devices. You convert to MP3 for compatibility, accepting a small quality trade-off.
Why is my MP3 bigger than the M4A?
MP3 is a less efficient codec, so matching the source's quality needs more bits — a 256 kbps AAC becomes a larger 320 kbps MP3. Choose a lower bitrate or the bitrate changer if size matters.
What input formats does it accept?
M4A and AAC primarily, plus MP3, WAV, FLAC, OGG, Opus and video — anything FFmpeg can decode. The output is always MP3. For other targets, use the matching converter such as the WAV or Opus tools.
Privacy first
Every JAD Audio tool runs entirely in your browser via FFmpeg (WebAssembly) and RNNoise. Your audio files never leave your device — verified by zero outbound network requests during processing.