Step 1: Attach your MP3 files using the button above or by bring and position.
Step 2: Click the 'Optimize' button to start the optimization.
Step 3: Collect your converted M4A files.
MP3 to M4A Optimization FAQ
What bitrate does the M4A file use?
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A lossy M4A is encoded at 192 kbps by default. The Audio Quality setting also offers 320 kbps for the best quality and 128 kbps for a smaller file. A lossless M4A (WAV, FLAC) ignores the bitrate and keeps every sample.
Will going from MP3 to M4A reduce my audio quality?
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If MP3 is lossy and M4A is lossless (e.g. MP3 -> WAV), the M4A file is no better than the MP3 — you cannot recover information that was already thrown away. If MP3 is lossless and M4A is lossy, the M4A codec recompresses; at 192 kbps this is transparent for most content.
Can I batch convert hundreds of MP3 files to M4A?
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Several files in one job need a paid plan. Free use is one file per conversion, one conversion an hour. On a paid plan you can add several files to one job, then download each result on its own or all of them in one ZIP.
Can I normalize loudness in the MP3 to M4A step?
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Not in this step. The converter has no loudness setting and leaves the level as it is. To even out the volume, run the finished M4A through a Normalize tool on this site.
Will the M4A play on my car stereo / iPod / Sonos?
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MP3 plays almost everywhere. AAC plays on Apple devices, most Android phones and Sonos. FLAC plays on Sonos and Android but not on older iPods, and WAV plays on nearly everything but makes large files. There are no device presets on this page, so choose the target format your player supports.
Is my MP3 file private during conversion?
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Yes. Uploaded MP3 files are processed on our own conversion servers, no person reviews them, and they are never shared. The upload and the converted M4A are both deleted automatically about 24 hours after the conversion, which leaves time to download the result. See /privacy/ for the full policy.
How long does converting a 1-hour MP3 to M4A take?
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It depends on the size and length of the file. Small documents and images are usually ready quickly. Long videos take the longest, because most video conversions re-encode every frame.
Why is the M4A file louder / quieter than the MP3 source?
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The converter does not change the level: it has no gain or normalize setting. If you hear a difference, your player or media library is probably applying ReplayGain or its own volume levelling on playback; switch that off to hear the M4A as it is.
Can I convert MP3 downloads to M4A?
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If the MP3 download is unprotected (no DRM), yes. DRM-encrypted streaming files (Spotify, Apple Music) are encrypted at the bit level and we cannot process them. Sources from Bandcamp, SoundCloud, and personal recordings convert fine.
