Add files from where they live
Drop a MP4 file on the box, browse for it, or import it from Dropbox, Google Drive or a link. You can add more files later, and each file gets its own result.
Free MP4 to MP3 converter
Convert MP4 to MP3 online. Add a file, confirm MP3 and download it. A single file needs no account.
Converting MP4 to MP3 keeps the soundtrack of a video and throws the picture away, leaving an audio file that is typically a small fraction of the original size. Because the audio in an MP4 is nearly always compressed already, it is re-encoded on the way out, so expect sound that matches the video closely, not a bit-perfect copy.
Transfers use HTTPS, and files converted on the free tier are deleted within 24 hours, so the result is not a long-term archive. Quality depends on the source file, so open the MP3 file once before you share it.
FromMP4Lossy
MP4 (MPEG-4 Part 14)
A video container that normally holds a picture stream, most often H.264 or HEVC, alongside one or more audio tracks, most often AAC. Phones, cameras, screen recorders and video call software all save recordings in it.
ToMP3Lossy
MP3 (MPEG-1 Audio Layer III)
An audio-only format with no room for pictures beyond a cover image. It stores a single mono or stereo stream compressed with a lossy codec, and it plays in every podcast app, music player and car stereo.
Why use indox to convert MP4 to MP3?
Watch the job run
A progress bar shows the file moving through the conversion. If you picked the wrong file, cancel and start again.
Download it or hand it on
Save the MP3 file, copy a share link or convert it to another format. Free-tier output expires on its own after 24 hours.
What changes
- All video is removed. Since the picture accounts for most of the data in an MP4, the MP3 is often a tenth of the size or less.
- The audio track, usually AAC, is decoded and compressed again as MP3, a second lossy pass that slightly reduces fidelity.
- Surround sound is folded down, because MP3 carries at most two channels, so a 5.1 film soundtrack becomes ordinary stereo.
- Subtitles, chapter markers, extra language tracks and video metadata have no place in an MP3 file and are left behind.
How do I convert MP4 to MP3 online?
- 1
Add your MP4 file
Drop your MP4 file into the converter (or choose a file from disk).
- 2
Pick MP3 and press Convert
Confirm MP3 as the output format and start the conversion.
- 3
Download the MP3 file
Download the MP3 file when it is ready. Start another conversion anytime.
What do I get from indox's MP4 to MP3 converter?
You upload a MP4 file, indox converts it to MP3, and you download the result. A single file needs no account, and nothing is installed.
- No install and no account for a single file
- MP3 output you can download or share
- Progress while the job runs, with a cancel button
- Free-tier files are deleted within 24 hours
What are the limits for MP4 to MP3?
Size
The upload box shows the live size limit before you add a file. Signing in raises it, and paid plans raise it further.
Formats
MP4 in, MP3 out. Pick another output on the converter if you need a different format.
Privacy
Files are encrypted in transit over HTTPS and processed on indox infrastructure.
Deletion
Free-tier files are deleted automatically within 24 hours after the job finishes.
Limits worth knowing
- A video with no audio track, such as some screen captures and security camera clips, gives an empty or failed result.
- When an MP4 holds several audio tracks, for example two languages or a commentary, typically only one ends up in the MP3.
- Sound quality is capped by the source. Phone video audio and heavily compressed web clips stay thin or noisy after conversion.
- Extracting audio does not change who owns it. Converting someone else's copyrighted video gives you no rights to use or share the soundtrack.
What do the free and paid plans add?
Free
- All converters
- Daily credit refresh
- Email support
Basic
- Access to all features
- AI Extract & Doc Chat
- Priority conversions
- Email support
Highest priority
Premium
- Everything in Basic
- Highest priority queue
- Larger file limits
- Priority support
Pay-As-You-Go
- No subscription
- Credits never expire
- Opt-in auto-refill
- Access to all features
Which conversions are close to MP4 to MP3?
Who can use a MP4 to MP3 converter?
When to use it
- Listening to a recorded lecture, webinar or sermon on a commute without keeping the screen on.
- Turning a video interview or Zoom meeting into audio for a transcription service or podcast edit.
- Saving the music from a concert, recital or band rehearsal you filmed yourself on a phone.
- Extracting a voice-over or sound effect from a finished clip to reuse in another project.
Where can I read more about converting files?
Do it all with indox
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MP4 to MP3 FAQs
Does converting MP4 to MP3 lose audio quality?
A little, because the sound is compressed twice. The AAC track inside the MP4 has already been through one lossy encoder, and writing MP3 applies another. With a decent source the result is indistinguishable for speech and fine for casual music listening. It cannot sound better than the video did, whatever the output bitrate.
How much smaller is the MP3 than the MP4?
Much smaller, commonly by a factor of ten to fifty. An hour of 1080p video can run from several hundred megabytes to a few gigabytes, while an hour of MP3 audio is roughly 58 MB at 128 kbps. The exact ratio depends almost entirely on how large the picture stream was, since that is what gets discarded.
Why is my MP3 silent or empty after converting a video?
Most likely the MP4 had no audio to extract. Screen recordings made without microphone or system sound, time-lapses, animations and many security camera files contain a picture stream only. Play the video in VLC or QuickTime and check the volume first. Less often, the track uses an unusual codec that the decoder cannot read.
Is it legal to convert a video to MP3?
It depends on whose video it is and where you live. Converting recordings you made or have permission to use is fine. Extracting audio from someone else's copyrighted film, music video or stream generally needs their consent, and private-copying rules differ by country. Changing the format never transfers any rights in the content.
Can I extract the audio from an MP4 without re-encoding?
Not as an MP3, in most cases. Copying the track untouched would give you the original AAC, which belongs in an M4A file, and MP3 is a different codec, so the audio must be encoded again to get there. The exception is the uncommon MP4 that already carries MP3 audio. Where a player accepts M4A, that route avoids the extra loss.
Which audio track is used if the video has more than one?
Usually the first or default track, since an MP3 can hold only one stream. Films with dubbed languages, director commentary or descriptive audio store each as a separate track inside the MP4. If the wrong one comes out, you would need to make a copy of the video containing only the track you want before converting it.