MP4 MP3

MP4 to MP3 Converter

Convert MP4 to MP3 in your browser. Free, private, and fast. Extract the audio track quickly without sending files to a server.

This converter runs a full FFmpeg engine in your browser. The first conversion downloads the engine (~31 MB, cached afterwards) — your file itself still never leaves your device.

Drag & drop your MP4 file here

or

Max file size: 50 MB · Your file stays in your browser

Your file is processed locally in your browser — nothing is ever uploaded.

Why Convert MP4 to MP3?

Converting MP4 to MP3 is a common task whenever a file has to work somewhere that expects the other format. MP4 is the world's most widely supported video container format. MP3 is the world's most widely supported audio format. This converter makes the switch locally in your browser — nothing is uploaded.

Common use cases

  • You have a MP4 file and need it in MP3 format.
  • The target software or platform requires MP3 but your file is in MP4.
  • Typical use of MP3: Music libraries, playlists, and portable players.
  • You want to reduce file size or improve compatibility without using desktop software.
Keep in mind: Lossy compression permanently discards some audio data. At very low bitrates, quality degradation becomes audible.

How to Convert MP4 to MP3

  1. Upload or drop your MP4 file into the converter above.
  2. Adjust any output settings for MP3 if needed.
  3. Click Convert and download your converted file instantly.

About the Formats

MP4 (MPEG-4 Part 14)

MP4 is the world's most widely supported video container format. It efficiently stores video (H.264 or H.265), audio, and subtitles in a single file with excellent compression.

Compatibility: Universal — supported by every browser, device, operating system, and video platform.

MP3 (MPEG Audio Layer III)

MP3 is the world's most widely supported audio format. Introduced in 1993, it uses psychoacoustic compression to dramatically reduce file sizes while preserving perceptible audio quality.

Compatibility: Universal — supported by every device, browser, media player, and platform.

100% Private & Browser-Based

Your files never leave your device. All conversion happens locally in your browser — nothing is uploaded to any server. No sign-up required.

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FAQ

Frequently Asked Questions

Yes — completely free with no sign-up, no watermarks, and no size limits for typical files.

MP3 uses lossy compression, which may reduce quality slightly compared to the original MP4. For most uses, the difference is imperceptible at standard quality settings.

Your file is processed entirely within your browser using local JavaScript. It is never uploaded to any server. Only you can access your file.

For browser-based conversion, files up to 50 MB work best. Very large files may take longer depending on your device. We recommend splitting very large files before converting.

Currently, AintoB converts one file at a time to keep the browser-based process simple and private. Reload the page to convert another file.