Free tool
M4A converter
This M4A converter turns any audio file, or a video’s sound, into an AAC M4A in your browser: AAC sound is copied as it is, and everything else is encoded at 96, 128 or 192 kbps. It also turns an M4A into MP3, WAV or OGG.
- Free
- AAC copied, not re-encoded
- 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 audio or video file here, or Choose your audio or video 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.
Many M4A files are iPhone voice memos and meeting recordings. NoteOwl imports M4A files and transcribes them on your Mac, with every speaker labelled and every word searchable.
How it works
How do you convert a file to M4A?
Leave M4A selected, choose a quality and drop the file. When its sound is already AAC, as in most M4A, MP4 and MOV files, the page moves it into the new M4A untouched. Anything else is decoded, then encoded to AAC by your browser. Play the M4A, then download it.
- 1
Pick a quality
96 kbps for speech, 128 kbps for everyday listening, 192 kbps for music. It only matters when the sound has to be encoded.
- 2
Add any file
MP3, WAV, FLAC, AIFF, OGG, an iPhone voice memo or a video, up to 1 GB and 2 hours long.
- 3
Save the M4A
It gets your file’s name with .m4a at the end, and keeps the title and artist.
How long does it take, and how big is the M4A?
Copying AAC takes a fraction of a second: a five-minute video’s sound in 0.07 seconds in Chrome. Encoding five minutes takes two to four seconds. Sizes differ by browser: on stereo speech, Chrome’s AAC encoder wrote less than the setting asked, and Safari’s engine wrote the full amount.
- MP4 video, AAC stereo 128 kbps, 33.4 MB
- How the M4A was madeAAC copied, no re-encoding
- Size (Chrome / WebKit)4.53 MB
- Took (Chrome / WebKit)0.07 s / 0.15 s
- Raw .aac, AAC-LC stereo 160 kbps, 5.68 MB
- How the M4A was madeAAC copied, no re-encoding
- Size (Chrome / WebKit)5.64 MB
- Took (Chrome / WebKit)0.08 s / 0.13 s
- WAV, 44.1 kHz stereo, 52.9 MB
- How the M4A was madeEncoded at 96 kbps
- Size (Chrome / WebKit)2.74 / 3.66 MB
- Took (Chrome / WebKit)1.9 s / 2.6 s
- The same WAV
- How the M4A was madeEncoded at 128 kbps
- Size (Chrome / WebKit)3.56 / 4.86 MB
- Took (Chrome / WebKit)2.2 s / 3.1 s
- The same WAV
- How the M4A was madeEncoded at 192 kbps
- Size (Chrome / WebKit)5.35 / 7.26 MB
- Took (Chrome / WebKit)2.4 s / 3.2 s
- MP3, 192 kbps stereo, 7.2 MB
- How the M4A was madeEncoded at 128 kbps
- Size (Chrome / WebKit)3.70 / 4.90 MB
- Took (Chrome / WebKit)2.4 s / 3.5 s
| File in | How the M4A was made | Size (Chrome / WebKit) | Took (Chrome / WebKit) |
|---|---|---|---|
| MP4 video, AAC stereo 128 kbps, 33.4 MB | AAC copied, no re-encoding | 4.53 MB | 0.07 s / 0.15 s |
| Raw .aac, AAC-LC stereo 160 kbps, 5.68 MB | AAC copied, no re-encoding | 5.64 MB | 0.08 s / 0.13 s |
| WAV, 44.1 kHz stereo, 52.9 MB | Encoded at 96 kbps | 2.74 / 3.66 MB | 1.9 s / 2.6 s |
| The same WAV | Encoded at 128 kbps | 3.56 / 4.86 MB | 2.2 s / 3.1 s |
| The same WAV | Encoded at 192 kbps | 5.35 / 7.26 MB | 2.4 s / 3.2 s |
| MP3, 192 kbps stereo, 7.2 MB | Encoded at 128 kbps | 3.70 / 4.90 MB | 2.4 s / 3.5 s |
When does the M4A keep the sound exactly as it was?
When the sound is AAC already. M4A, MP4, MOV and raw .aac files usually carry AAC, so the converter copies those frames into the new file with no re-encoding: nothing is lost, and five minutes takes well under a second. Every other kind of sound has to be encoded.
That makes an M4A the cleanest way to keep a phone video’s sound on its own: a 33.4 MB, five-minute video gave a 4.53 MB M4A in 0.07 seconds. The quality menu is ignored for a copy.
Why is the M4A smaller in Chrome than in Safari?
Because the two browsers’ AAC encoders spend bits differently. On a five-minute stereo WAV of speech, Chrome’s 192 kbps setting produced 5.35 MB, about 143 kbps on average, while Safari’s engine wrote 7.26 MB, the full 192. Both are standard AAC-LC files.
Chrome’s encoder also takes only 44.1 or 48 kHz, so every encoded M4A is written at one of those rates in either browser: sources at 48 kHz or above get 48 kHz, everything else 44.1 kHz. Copied AAC keeps its own rate, and more than two channels are mixed down to stereo.
What’s the difference between M4A, M4B and MP4?
Mostly the name. All three are MPEG-4 files. M4A holds sound only, M4B is the same audio format named so that players treat it as an audiobook, and MP4 usually carries video as well. The converter reads all three, and writes M4A.
- .m4a
- What it holdsSound only: AAC, or Apple Lossless
- Where you see itiPhone and Mac Voice Memos, music downloads, Zoom’s audio-only file
- .m4b
- What it holdsSound, usually AAC, often with chapters
- Where you see itAudiobooks
- .mp4
- What it holdsVideo and sound, the sound usually AAC
- Where you see itPhones, cameras, screen and meeting recordings
- .aac
- What it holdsAAC frames with no MP4 container
- Where you see itRadio stream recordings, some recorder apps
| Ending | What it holds | Where you see it |
|---|---|---|
| .m4a | Sound only: AAC, or Apple Lossless | iPhone and Mac Voice Memos, music downloads, Zoom’s audio-only file |
| .m4b | Sound, usually AAC, often with chapters | Audiobooks |
| .mp4 | Video and sound, the sound usually AAC | Phones, cameras, screen and meeting recordings |
| .aac | AAC frames with no MP4 container | Radio stream recordings, some recorder apps |
Can you turn an M4A into another format here?
Yes. Open Save as and pick MP3, WAV or OGG before you drop the file. MP3 plays anywhere, WAV is uncompressed for editing, and OGG holds Opus for the smallest files. A five-minute voice-memo M4A became a 7.2 MB MP3 at 192 kbps in 2.1 seconds in Chrome.
Each trip has its own page with its own measurements: M4A to MP3 and M4A to WAV out of the format, MP3 to M4A and WAV to M4A into it.
One kind of M4A needs Safari: Apple Lossless, which Voice Memos records when its audio quality is set to Lossless. Chrome has no decoder for it.
What does NoteOwl do with an M4A recording?
It imports it on your Mac as it is, transcribes it with on-device AI models, names each speaker and keeps the transcript searchable alongside your meetings. iPhone voice memos are M4A already, so there is nothing to convert first. Dictation into any app is free.
There is a step-by-step guide to transcribing a voice memo on a Mac.
FAQ
Common questions about M4A files
Is anything uploaded when I convert to M4A?
No. The file is read from your device and the M4A is put together inside your browser, either by copying the AAC that is already there or with the browser’s own AAC encoder. Nothing is uploaded.
Does converting to M4A lose quality?
Not when the sound is AAC already: it is copied, not re-encoded. Other sound is encoded to AAC, which drops a little detail, more at 96 kbps than at 192. A lossless source such as WAV or FLAC keeps the most at 192 kbps.
Can it open Apple Lossless voice memos?
In Safari, yes, up to 30 minutes long, because Safari reads such a file whole. Chrome has no Apple Lossless decoder, so it says so and points you to Safari. Voice Memos makes these files when its audio quality is set to Lossless.
Which sample rate does the M4A use?
48 kHz for sources at 48 kHz or higher, and 44.1 kHz for everything else, since Chrome’s AAC encoder accepts only those two rates. Copied AAC sound keeps whatever rate it was recorded at.
Will an M4A play on Android and Windows?
Yes. Android phones play AAC M4A files, and so do the media players built into Windows 10 and 11, as well as Chrome, Safari and VLC.
Can it make an M4B audiobook?
It writes .m4a files. Because M4B is the same format, renaming the ending from .m4a to .m4b is enough for Apple Books to file it as an audiobook. The converter adds no chapters.
How long a file can it make into an M4A?
Up to 2 hours and 1 GB. A 70-minute MP3 became a 128 kbps M4A of 49.8 MB 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
- Video to MP3 converterTurn any video’s sound into an MP3 in your browser: MP4, MOV, MKV, WebM and 3GP, at 128, 192 or 320 kbps; nothing is uploaded
- MP3 to WAV converterConvert MP3 to WAV in your browser: 16-bit PCM at the MP3’s own sample rate or 44.1 kHz, ready for editors and samplers; nothing is uploaded
- MP3 to OGG converterConvert MP3 to OGG (Opus) in your browser at 32, 64 or 128 kbps: the format of WhatsApp and Telegram voice messages; nothing is uploaded
Related
- M4A to MP3 converterConvert M4A to MP3 in your browser, iPhone and Mac voice memos included, at 128, 192 or 320 kbps; nothing is uploaded
- M4A to WAV converterConvert M4A to WAV in your browser, iPhone voice memos included: AAC or Apple Lossless in, 16-bit WAV out; nothing is uploaded
- MP3 to M4A converterConvert MP3 to M4A (AAC) in your browser at 96, 128 or 192 kbps, for iPhone, iPad and Mac apps; nothing is uploaded
M4A recordings into notes you can search, 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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