Use the free MP4 to MP3 Converter below. Your file never leaves your device.
What this tool does
This MP4 to MP3 Converter takes a video file and gives you back only its sound, as an MP3 file. You choose a video on your device, the tool reads the audio track inside it, and it builds a new MP3 for you to download. Nothing is uploaded. The video never leaves your device, because all the work happens in your browser.
The sound is not copied out of the video unchanged. It is decoded and then re-encoded as MP3. That matters, because MP3 is a lossy format. Lossy means the encoder drops some fine detail that most listeners will not notice, in order to make the file small. You get a handy listening file, not an exact copy.
How to use it
First, press the file button and choose an MP4 video from your device. The tool reads the audio track and shows its length, channel count, sample rate, and file size. It also draws a wave picture of the sound, so you can see loud and quiet parts from start to finish.
Next, choose a bitrate. The bitrate sets how much data the MP3 keeps each second. Then press Convert to MP3. When the result appears, you can play it in the page to check it, and then download it. To change the balance of size and quality, change the bitrate and convert again.
Worked example with a real test file
We tested this tool with a real two second MP4 made for testing. The test video was 44.6 KB, with a single audio channel at 44,100 Hz. After decoding, the tool showed a length of 2.0 seconds and drew the wave picture of the tone in the file.
With the bitrate set to 192 kbps, the tool produced an MP3 of 48,901 bytes, about 47.8 KB. The output played back at about 2.04 seconds, which includes a small amount of padding that MP3 encoders add at the end. The first bytes of the file were FF FB, which is the frame sync pattern that marks a real MP3 frame. That check matters, because it proves the download is a genuine MP3, not a renamed file.
Note that the MP3 is slightly larger than this small test video, which can happen with very short clips. With a normal length video, the MP3 is usually much smaller, because the picture data is left out.
Which bitrate should you choose
Choose 128 kbps when size matters most, for example when you want to send the sound quickly or store many clips. The sound is clear for speech and most everyday listening. Choose 192 kbps for a good balance, which suits music and longer recordings. Choose 320 kbps when you want the clearest MP3 this tool can make, and you do not mind a bigger file.
No bitrate can restore detail already lost in the source video. A higher bitrate only avoids adding new loss on top of it.
Good uses for this tool
This tool suits simple, everyday jobs. You can pull the sound from a lecture recording so you can listen while you walk. You can take the audio from a family video to keep as a listening file. You can grab the sound from a short clip to use as a ringtone base, or to review a spoken note without watching the picture.
It also suits quick checks. An MP3 is faster to open and easier to share than the full video.
Honest limitations
This tool works with the audio track of a video your browser can decode. An MP4 file with a normal audio track works well. A file with no audio track has nothing to convert, and the tool will say so. A damaged file, or a format your browser cannot decode, may fail, and the tool will show a plain error instead of a fake result.
The output is always MP3, and MP3 is always lossy. Do not use it for exact, studio grade editing; WAV is better for that. A very long video can also take a while, because the whole file is decoded in your browser.
Finally, only convert videos you have the right to use. If a video belongs to someone else, or carries music you do not own, converting it does not give you the right to share it.
Frequently asked questions
Does my video leave my device?
No. The file is read in your browser only. It is not uploaded to a server, and no account is needed.
Is the MP3 an exact copy of the video sound?
No. The audio is decoded and re-encoded as MP3, which is lossy. It sounds close to the original, but it is not a bit exact copy.
Why is my MP3 bigger than my short video?
Very short clips can show this effect, because the encoder adds a little padding and the video itself was already small. With normal length videos, the MP3 is usually much smaller than the video.
Can I convert a video with no sound?
No. If there is no audio track, there is nothing to turn into an MP3. The tool will report that no audio was found.
Spanish version: Extractor de Audio de MP4 a MP3 Rápido en el Navegador