MP3 to M4A
Convert MP3 to M4A, if you need to.
Drop MP3 files and get M4A copies at 128, 192 or 320 kb/s. Title, artist and album come along, and nothing is uploaded.
Needs a browser that can make M4A sound itself. Tested in Chrome and in WebKit, the engine behind Safari; Firefox is not tested.
Drop a song here.
Drop a song here.Choose a song.
MP3WAVFLACM4ANothing leaves this device.
Several files of one kind convert together.
How it works
Choose a quality and convert.
1
Drop the MP3s
Single tracks, albums or a podcast archive. Variable and constant bitrate MP3 are both read.
2
Choose a quality
Plays everywhere is selected, which is 192 kb/s. Match or go slightly below the MP3's own bitrate, since going higher adds only size. Small file is 128 kb/s.
3
Save
M4A with the title, artist and album of the MP3. The cover picture is not carried over.
Measured examples
A bigger file from a smaller one.
A generated 90-second 192 kb/s MP3, converted at this page's setting of 192 kb/s in Chrome and in WebKit.
| Test file | Size | Change | Time | Result |
|---|---|---|---|---|
| 90 s musicChrome | 2.2 MB → 1.7 MB | 22 percent smaller | 1.5 s | |
| 90 s musicWebKit | 2.2 MB → 2.2 MB | 1 percent larger | 4.2 s | |
| 90 s music with tags and coverChrome | 2.2 MB → 1.7 MB | 22 percent smaller | 1.5 s | Title, artist and album kept · Cover not kept |
| 90 s music with tags and coverWebKit | 2.2 MB → 2.2 MB | 1 percent larger | 4.3 s | Title, artist and album kept · Cover not kept |
Measured on November 7, 2026 in Google Chrome 157, WebKit (Playwright build, not Safari) 26, on Apple M1 Pro. Times run from pressing Convert to the result being ready, with the page already loaded. Likeness is PSNR against the original: higher is closer, and above 40 dB the difference is hard to see. WebKit here is Playwright's build, which is not Safari. Every test file was generated for these measurements, none is anyone else's work, and each is described on the About page.
The 2.2 MB MP3 became 1.7 MB in Chrome and 2.2 MB in WebKit. In WebKit the M4A is larger than the MP3 it came from, and in neither browser did the conversion add any quality: a second lossy pass cannot give back what the first one removed. The tags came across and the embedded cover did not.
Facts
What the M4A keeps.
Tags
Title, artist and album from the ID3 tag came across in both browsers.
Cover picture
Dropped on the way. The ID3 cover of our test MP3 did not reach the M4A.
Length
The M4A ran 54 to 69 milliseconds longer than the MP3 in our tests: the encoder's start delay and the MP3 decoder's padding.
Quality
Never better than the MP3. The best result is close to it.
Good to know
An honest page about a lossy-to-lossy step.
MP3 and AAC both discard sound. Converting between them is sometimes needed and almost never an upgrade.
It will not sound better
Each lossy encode throws away detail. An MP3 turned into AAC has been through two, so the best you can get is close to the MP3. A 320 kb/s M4A made from a 128 kb/s MP3 is larger and no better. Start from the original CD rip or FLAC if you still have it.
Reasons that do hold up
Some apps and devices want M4A or AAC and refuse MP3. Smaller files are a reason too: a 320 kb/s MP3 is 2.4 MB per minute, and 128 kb/s AAC about 1 MB, a saving of roughly 60 percent. For speech and podcasts that is usually fine.
Timing and tags
The converted file runs a little longer, 54 to 69 milliseconds in our tests, because of the encoder's start delay and padding. It does not use gapless information from the MP3, so live albums can show small gaps. ID3 title, artist and album come along; the cover picture does not.
Speed and size
A 3-hour 192 kb/s MP3 of 259 MB became an M4A in about a minute in Chrome and under two minutes in WebKit, the engine behind Safari. The audio never leaves the tab.
Podcasts and audiobooks
Speech is where this conversion makes the most sense. Voices need far less bitrate than music, so a 128 kb/s M4A of a talk is about a megabyte a minute and sounds the same as the MP3 it came from. Audiobook and podcast apps handle M4A well.
If something goes wrong
When it does not work.
The honest cases for this page, and the ones against it.
The M4A is not smaller
Why: A 192 kb/s MP3 converted at 192 kb/s gives a file of about the same size: 2.2 MB from 2.2 MB in WebKit.
What to do: Pick 128 kb/s for speech, or keep the MP3 if nothing needs M4A.
The cover art is gone
Why: The cover picture is not carried over from the MP3.
What to do: Add it again in a tag editor.
It sounds a little worse
Why: Two lossy encodes in a row throw away more than one.
What to do: Go back to the original CD rip or FLAC if you still have it.