Free tool
MP3 to M4A converter
Drop an MP3 here to convert MP3 to M4A in your browser: you get AAC sound in an .m4a file at 96, 128 or 192 kbps, with the title and artist carried over and nothing uploaded.
- Free
- Works on phones
- Nothing is uploaded
Save as
M4A quality
AAC sound in an M4A file, for Apple devices and apps. AAC sound, such as a video’s, is copied as is; other sound is encoded at the quality you pick.
Drop your MP3 file here, or Choose your MP3 file
Any audio or video file, up to 1 GB and 2 hours. It’s converted in your browser; nothing is uploaded.
MP3 encoding by LAME, open-source software.
Is the MP3 a recorded call or a lecture? NoteOwl imports MP3 as it is, so there’s no M4A to make first, and transcribes it on your Mac with each speaker labelled.
How it works
How do you change an MP3 into an M4A?
Pick 96, 128 or 192 kbps and drop the MP3. Your browser decodes it, and its own AAC encoder writes the sound into an .m4a file, at 44.1 kHz for a typical MP3. Five minutes took about two seconds in Chrome.
- 1
Choose the AAC bitrate
Match the MP3 where you can: 192 kbps for a 192 or 320 kbps MP3, and lower settings for speech.
- 2
Drop the MP3
Constant or variable bitrate, mono or stereo. It is decoded on your own device.
- 3
Download the M4A
Listen, then save it. Title and artist tags come across from the MP3, and the file name now ends in .m4a.
What size M4A do you get from an MP3?
Smaller than the MP3 at 96 and 128 kbps, and close to it at 192. On stereo speech Chrome’s AAC encoder spends less than asked, so its files come out lighter than Safari’s, which writes the bitrate you pick. Both make AAC-LC.
- 96 kbps
- M4A in Chrome2.82 MB
- M4A in WebKit3.70 MB
- Time, Chrome / WebKit2.0 s / 3.2 s
- 128 kbps
- M4A in Chrome3.70 MB
- M4A in WebKit4.90 MB
- Time, Chrome / WebKit2.4 s / 3.5 s
- 192 kbps
- M4A in Chrome5.46 MB
- M4A in WebKit7.30 MB
- Time, Chrome / WebKit2.3 s / 3.6 s
| AAC setting | M4A in Chrome | M4A in WebKit | Time, Chrome / WebKit |
|---|---|---|---|
| 96 kbps | 2.82 MB | 3.70 MB | 2.0 s / 3.2 s |
| 128 kbps | 3.70 MB | 4.90 MB | 2.4 s / 3.5 s |
| 192 kbps | 5.46 MB | 7.30 MB | 2.3 s / 3.6 s |
Do you need to convert an MP3 for Apple Music or an iPhone?
Usually not. Apple Music, the Music app on a Mac, imports MP3 files as they are, and an iPhone or iPad plays them without help. Convert when an app, a course site or an upload form asks for .m4a, or when you want a smaller AAC copy.
On an iPhone, an MP3 saved to the Files app plays straight from there. Spoken word is where an M4A earns its place: at 96 kbps the five-minute test MP3 shrank from 7.2 MB to 2.82 MB in Chrome and 3.70 MB in Safari’s engine.
Will the M4A sound better than the MP3 it came from?
No. AAC tends to beat MP3 at equal bitrates, but only when it starts from the original recording. Made from an MP3, it can hold only what the MP3 kept, and a second lossy encoding sheds a little more.
So treat the MP3 as the best copy you have: convert it at 192 kbps, or leave it alone. If the WAV or the original recording still exists, make the M4A from that with the WAV to M4A converter instead.
Why are the M4A files smaller in Chrome than in Safari?
The two browsers ship different AAC encoders. On stereo speech, Chrome’s spends less than the setting: “192 kbps” averaged about 145 kbps on the test MP3. Safari’s writes the bitrate you choose. Both files are AAC-LC and play wherever M4A does.
The settings are identical in both; only the encoder differs. So when a service checks an upload for a minimum bitrate, make the M4A in Safari, whose file carries the number you picked.
Which sample rate does the M4A use?
44.1 kHz for a 44.1 kHz MP3, which most music MP3s are, and 48 kHz for one made at 48 kHz. An MP3 at another rate, such as a 22.05 kHz voice recording, is written at 44.1 kHz: Chrome’s AAC encoder works at those two rates only.
Can NoteOwl work with the MP3 itself?
Yes. NoteOwl imports MP3 and M4A alike, so nothing needs converting for it. On a Mac it transcribes the recording with on-device AI models, labels each speaker and files the transcript where meeting search can find it later.
FAQ
Questions about changing MP3 files to M4A
Is my MP3 uploaded to convert it?
No. Decoding and AAC encoding both happen inside your browser, on your device, and neither the MP3 nor the M4A is uploaded. You don’t need an account either.
Is M4A the same as AAC?
Almost. AAC is the sound; M4A is the MPEG-4 file that holds it. The converter writes AAC-LC, the most widely supported kind, into an .m4a file that iPhone, iPad, Mac, Windows and Android all play.
Which AAC bitrate should I choose?
192 kbps for music, the highest setting here and the right one for an MP3 made at 192 or 320 kbps. 128 kbps sits in the middle for podcasts and talks, and 96 kbps is for keeping spoken word as small as it will go.
Is the M4A an iPhone ringtone?
No. A ringtone is a short AAC clip with the .m4r ending, and this page writes full-length .m4a files without trimming them. The M4A plays in the Music app like any song.
Does the M4A keep the song title and artist?
Yes. The title and artist from the MP3’s ID3 tag are written into the M4A’s own tags, so players that read tags show them. The file keeps its name too, ending in .m4a.
Can I turn the M4A back into an MP3 later?
Yes, by choosing MP3 in the same converter, but every round trip between lossy formats re-encodes the sound and costs a little more detail. If you might need the MP3 again, keep the original file beside the M4A.
How long an MP3 can it convert?
Up to 2 hours and 1 GB. A 70-minute MP3 of 100.8 MB became a 49.8 MB M4A at 128 kbps in 28 seconds in Chrome.
Keep exploring
More audio converters
- Audio converterConvert audio and video files to MP3, WAV, M4A or OGG in your browser: M4A, FLAC, AIFF, OGG, Opus, WebM, MP4 and MOV in; nothing is uploaded
- AAC to MP3 converterConvert raw .aac files (ADTS), from radio recorders, Android apps and stream rips, to MP3 in your browser; nothing is uploaded
- Opus to MP3 converterConvert .opus files, such as WhatsApp voice notes and downloaded audio, to MP3 in your browser; nothing is uploaded
- WAV to M4A converterShrink a WAV into an AAC M4A in your browser at 96, 128 or 192 kbps, about 7 to 19 times smaller; nothing is uploaded
MP3 recordings into notes, on your Mac
Free to download. Runs entirely on your Mac.
macOS 26 or later · Apple Silicon (M1 or newer) · 16 GB memory minimum, 24 GB recommended
About NoteOwl
NoteOwl is private AI meeting notes and memory for the Mac. It captures meetings without a bot joining the call, labels every speaker, writes summaries and action items, and builds a memory of every conversation that you can chat with — fully offline, because the speech recognition and the AI run on the Mac itself. Dictation into any app is free; Pro is a one-time purchase.
NoteOwl pricing: what’s free and what Pro adds
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