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MP3 → MP4

MP3 to MP4 Converter

Wrap audio inside an MP4 so platforms that only accept video will take it. Add a cover image for a still-frame video, or leave it audio-only.

FreeNo sign-upNo upload — runs on your device

Drop an audio file here, or click to browse

Accepted: .mp3 .m4a .wav .aac .flac .ogg · up to 2 GB

Add a JPG or PNG to use as the still frame. Without it you get an audio-only MP4.

Before you start

  • · The first conversion downloads the FFmpeg engine (about 32 MB). It is cached afterwards.
  • · Keep files under 2 GB, and under a few hundred MB if you are on a phone or re-encoding video.
  • · Keep this tab in the foreground — browsers throttle background tabs and the conversion will pause.

How to convert MP3 to MP4 in 3 steps

  1. 1

    Add your audio file

    Drop in an MP3, M4A, WAV, AAC or FLAC file. Anything your browser can read works as the audio source.

  2. 2

    Optionally add a cover image

    Upload a JPG or PNG and it becomes the still frame of the video. Skip it if you only need an MP4 container around the audio.

  3. 3

    Convert to MP4

    Press Convert. Audio is encoded to AAC, the cover is turned into a one-frame-per-second video, and the result downloads as a standard MP4.

About MP3 and MP4

Why audio needs an MP4 wrapper

Some platforms only accept video files. YouTube in particular will not publish a bare audio file, and neither will several social and podcast distribution systems. Wrapping the audio in an MP4 satisfies the upload check while keeping the content purely audio — and if you supply a cover image, the result looks like an ordinary still-image video rather than a blank frame.

How the cover image is handled

When you add a cover, FFmpeg loops the image and encodes it at one frame per second with the still-image tune, which keeps the file small and the CPU cost low. Audio is encoded to AAC at your chosen bitrate and the streams are muxed into a faststart MP4 so it begins playing before the whole file is downloaded. Without a cover you get an audio-only MP4 — valid, tiny, and accepted by tools that reject MP3.

Choosing a bitrate

192 kbps AAC is transparent for most listeners and produces a file that is smaller than the equivalent MP3 in many cases. Drop to 128 kbps for speech-only content, or go to 256 kbps when the source is high-quality music and you want headroom. Going above the source bitrate does not add quality, only size.

Frequently asked questions

How do I convert MP3 to MP4 for free?
Add the audio file at the top of this page, optionally choose a cover image, and press Convert. No account, no watermark and no limit.
Do I need a cover image?
No. Without one you get an audio-only MP4, which is smaller and works anywhere an MP4 is required. Add an image when the platform expects something that looks like a video.
Will the MP4 play on YouTube?
Yes. The output is a standard H.264 and AAC MP4, which is exactly what YouTube accepts. Adding a cover image gives you a still-frame video suitable for uploading.
What is the best bitrate to choose?
192 kbps is a good default for music and podcasts. Use 128 kbps for spoken word and 256 kbps when the source audio quality justifies it.
Can I convert a video into an MP3 first and then into MP4?
You can, but there is no need — the MOV to MP4 and MKV to MP4 tools handle video directly, and MOV to MP3 handles audio extraction.
Is the conversion processed on your servers?
No. Encoding happens locally with WebAssembly, so your audio and images never leave your device.

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