Is the video uploaded anywhere?

No. The conversion runs inside your browser using the same audio decoder your computer uses to play the file, so the MP4 never leaves your device. You can check for yourself: open your browser’s developer tools, watch the network tab, and convert something. Nothing carrying the video is sent. This is unusual — almost every other MP4 to MP3 converter uploads the whole video to a server to strip three megabytes of audio out of it.

How long does a two-hour video take?

Usually under a minute, and often far less. The audio is decoded and re-encoded at many times real time, so the length of the recording matters much less than people expect. What does take time is reading a very large file from a slow disk or a phone. There is no queue and no upload, so the only limit is your own machine.

Does the MP3 lose quality compared to the video’s sound?

A little, and it is unavoidable. The audio inside an MP4 is almost always AAC, which is already compressed; turning it into MP3 compresses a second time, so some detail is lost twice over. For speech it is inaudible. For music, choose the high quality setting under the result — or convert to M4A instead, which keeps the original AAC audio without re-encoding it at all.

Can I convert several videos at once?

Yes. Drop up to a hundred files onto the page and each converts on its own, with its own progress. When more than one has finished you can download them together as a ZIP. Because nothing is uploaded, a batch costs you no bandwidth and us nothing at all.

Does this work on an iPhone or an Android phone?

Yes, in the browser you already have. There is nothing to install and no account. A phone converts an MP4 to an MP3 exactly the way a laptop does, which is worth knowing if the video is on the phone in the first place — you avoid moving it to a computer just to strip the audio out.

What if the video has more than one soundtrack?

Only the first is kept. A film with a second language or a director’s commentary loses those tracks, because an MP3 holds exactly one. If you need a specific track, that is a job for editing software rather than a converter.

MP4toMP3

Convert MP4 to MP3

Up to 100 files at once. Mixed formats are fine.

Converting MP4 to MP3 keeps the sound and throws away the picture, which is what you want for a lecture, a podcast or a song trapped inside a video. Drop the file above and it converts inside your own browser — the video is never uploaded, there is no account, and a two-hour recording usually takes well under a minute.

Why this conversion normally means uploading your video, and why it does not here

An MP4 is a container. Inside it sit two separate streams — the picture and the sound — and pulling the sound out is, in principle, a matter of ignoring one of them. In practice almost every converter on the internet does this by uploading the entire video to a server, running ffmpeg on it, and sending back a file a fraction of the size. A one-gigabyte lecture recording travels across the internet twice so that thirty megabytes of speech can come back.

That is a strange amount of work for the result, and it means handing a recording to a company you have never heard of. This page does it differently: your browser already contains the decoders needed to play an MP4, because it plays them on every website you visit. We use those, so the video stays on your machine and the only thing that moves is the finished MP3, from one part of your computer to another.

What governs the size of the MP3

The length of the recording, almost entirely. Audio is roughly one megabyte per minute at ordinary quality, so an hour-long lecture lands near sixty megabytes regardless of whether the video it came from was two hundred megabytes or two gigabytes. The picture is what makes video files large, and the picture is exactly what this conversion discards.

The quality control under the result moves that number up or down by about a factor of two in each direction. Balanced is the default and is transparent for speech and most listening. Choose the smaller setting for something you will play through a phone speaker on a train, and the higher one for music you care about.

MP3 or M4A: the choice worth thirty seconds

The audio inside an MP4 is almost always AAC. Converting it to MP3 means decoding that AAC and encoding it again as MP3, and every re-encode of already-compressed audio loses a little more. For speech this is genuinely inaudible. For music it is measurable and, on good headphones, sometimes noticeable.

Converting the same MP4 to M4A instead keeps the AAC exactly as it is — the file is repackaged rather than re-encoded, so nothing at all is lost and it is usually faster. The catch is compatibility: MP3 plays on everything ever made, including car stereos, gym equipment and twenty-year-old MP3 players, while M4A wants something reasonably modern. If the file is going to a phone or a computer, M4A is the better answer. If it is going anywhere else, MP3 is the safe one.

Converting a batch of videos

Drop up to a hundred files at once. Each converts independently with its own progress bar, and once two or more have finished a single button offers all the results as a ZIP. Nothing is queued behind anyone else, because there is no shared server — the work happens on your machine, so the only thing that limits a batch is how much your own computer feels like doing.

This is the point at which the no-upload approach stops being a privacy argument and becomes a practical one. Converting forty lecture recordings through a site that uploads them means forty uploads and a daily limit; here it means leaving a tab open.

What the MP3 will not carry over

Chapters, subtitles and any second audio track are lost, because an MP3 has nowhere to put them. Only the first soundtrack survives, which matters for films with a commentary or a dubbed language but almost never for a recording of somebody talking.

Cover art and title metadata from the video are not carried across either. If the MP3 is going into a music library, expect to set the artist and album yourself — that is a job for a tagging tool rather than a converter, and doing it badly is worse than not doing it.

How to get the audio out of an MP4

Drop your MP4 onto this page, or click to choose one. Several at once is fine.
The audio is extracted and encoded inside your browser — nothing is uploaded.
Download the MP3, or change the quality under the result and convert again.

What actually changes when an MP4 becomes an MP3

MP4 compared with MP3
	MP4	MP3
Full name	MPEG-4 Video	MPEG Audio Layer III
File extension	.mp4	.mp3
Media type	video/mp4	audio/mpeg
Compression	Lossy — file size is bought with quality	Lossy — file size is bought with quality

Quality: Some quality is given up for a smaller file. At the default setting the difference is hard to see.
Where it runs: This conversion runs inside your browser. Your file is never uploaded, and it works with the network disconnected.
What can be lost: Only the first soundtrack is kept. A film with a second language or a commentary track loses it.

MP4 to MP3: the questions people actually ask

Is the video uploaded anywhere?: No. The conversion runs inside your browser using the same audio decoder your computer uses to play the file, so the MP4 never leaves your device. You can check for yourself: open your browser’s developer tools, watch the network tab, and convert something. Nothing carrying the video is sent. This is unusual — almost every other MP4 to MP3 converter uploads the whole video to a server to strip three megabytes of audio out of it.
How long does a two-hour video take?: Usually under a minute, and often far less. The audio is decoded and re-encoded at many times real time, so the length of the recording matters much less than people expect. What does take time is reading a very large file from a slow disk or a phone. There is no queue and no upload, so the only limit is your own machine.
Does the MP3 lose quality compared to the video’s sound?: A little, and it is unavoidable. The audio inside an MP4 is almost always AAC, which is already compressed; turning it into MP3 compresses a second time, so some detail is lost twice over. For speech it is inaudible. For music, choose the high quality setting under the result — or convert to M4A instead, which keeps the original AAC audio without re-encoding it at all.
Can I convert several videos at once?: Yes. Drop up to a hundred files onto the page and each converts on its own, with its own progress. When more than one has finished you can download them together as a ZIP. Because nothing is uploaded, a batch costs you no bandwidth and us nothing at all.
Does this work on an iPhone or an Android phone?: Yes, in the browser you already have. There is nothing to install and no account. A phone converts an MP4 to an MP3 exactly the way a laptop does, which is worth knowing if the video is on the phone in the first place — you avoid moving it to a computer just to strip the audio out.
What if the video has more than one soundtrack?: Only the first is kept. A film with a second language or a director’s commentary loses those tracks, because an MP3 holds exactly one. If you need a specific track, that is a job for editing software rather than a converter.