Convert MP4 to MP3
Pull the audio out of a video and save it as an MP3. Drop in an MP4 (or most other video formats), pick a bitrate, and In1 extracts the soundtrack right in your browser. Your video is never uploaded — the whole conversion runs on your device.
How to use MP4 to MP3
- 1
Add your video
Drag an MP4 or other video file into the drop area, or click to choose one from your device.
- 2
Pick a bitrate
Choose the MP3 quality — higher for music, lower for spoken word and smaller files.
- 3
Convert
Click convert and In1 extracts the audio locally in your browser. The first run loads the engine.
- 4
Download the MP3
Save the extracted audio. Your video was never uploaded anywhere.
Get just the audio from any video
Often the part of a video you actually want is the sound: a song, a podcast or interview recorded as video, a lecture, a sermon, a voice memo someone filmed, or the audio from a clip you want to listen to on the go. Converting MP4 to MP3 strips away the picture and keeps the soundtrack as a compact audio file you can play anywhere — in a music app, on a phone during a commute, in the car, or on a smart speaker. In1 reads the video, extracts its audio track and re-encodes it as an MP3 in a single step. There is nothing to configure beyond the quality you want, and because MP3 is the most universally supported audio format on the planet, the result will play on essentially any device or app without compatibility headaches. Stripping the video also shrinks the file dramatically — audio is a small fraction of a video's size — which makes the MP3 far easier to store on a phone, attach to a message, or sync to a player. And once it is audio-only, you can listen with the screen off, something a video file will not let you do, which is exactly what you want for a podcast or a long lecture you plan to play in the background.
Choose the audio quality you need
MP3 lets you trade file size against audio fidelity, and In1 puts that choice in your hands with a bitrate selector. A higher bitrate like 256 or 320 kbps keeps the audio crisp and is the right pick for music or anything where sound quality matters. A lower bitrate like 128 kbps produces a much smaller file that is perfect for spoken-word content such as podcasts, lectures and interviews, where ultra-high fidelity is unnecessary and a small file is more convenient to store and share. The default sits in the middle at a balanced setting that sounds good for almost everything. Being able to pick the bitrate means you are never stuck with a needlessly huge file for a simple voice recording, or a low-quality file for your favorite track.
Runs in your browser — private and free
This conversion happens entirely on your own device. The video is processed in your browser using ffmpeg compiled to WebAssembly, so your file is never uploaded to a server, never stored and never seen by anyone else. That privacy matters: home videos, recordings of family and friends, confidential meetings and unreleased footage are exactly the kind of thing you should not be handing to a random website. With In1 there is no upload, no account, no watermark on the output and no daily limit. The trade-off for keeping everything local is that the work uses your device's processor, so very long videos take longer to convert — but for the typical clip, song or talk, extraction finishes in a reasonable time, and you never have to wait on an upload or a server queue.
The first conversion loads the engine
Because the conversion engine runs locally, the ffmpeg core has to be downloaded to your browser the first time you use a video or audio tool on In1. That download happens once and is then cached, so subsequent conversions start much faster. While it loads and while your file is processing, a progress indicator keeps you informed so you know the tool is working and has not stalled. To keep things responsive and avoid running out of memory, there is a sensible size limit on the video you can convert — browser-based processing holds the file in memory, so extremely large videos are best trimmed or handled by a desktop application. For everyday clips, songs and recordings, though, the in-browser approach is fast, private and completely free.
Who converts MP4 to MP3 and why
The reasons are everywhere. Music lovers pull the audio from a music video to listen offline. Students and professionals turn recorded video lectures, webinars and meetings into MP3s they can replay on the move. Podcasters and content creators who recorded on video extract the audio track to publish or edit as a podcast. People save the sound from a clip — a speech, a comedy bit, a guided meditation — to keep just the part they care about. Others convert videos to MP3 simply to save space, since an audio file is a fraction of the size of the video. Whatever the motivation, the goal is the same: separate the sound from the picture and get a clean, portable MP3 — quickly, privately and for free, without installing any software. It pairs naturally with the audio converter too: extract an MP3 here, then convert it to WAV, OGG or M4A if a particular device or app prefers a different format. Having both tools side by side means you can go from a raw video to exactly the audio file you need in a couple of quick, private steps on your own machine.
Higher limits, batch processing and an API are on the way. Want early access?