MP3 to MP4, with a picture or a moving waveform.

To convert MP3 to MP4 is to put the sound into a video file, because an MP3 is only sound and a video file also needs a picture. This tool makes that video in your browser. Drop an MP3 and the cover art inside it is used as the picture, or choose any image of your own, or let a waveform move with the music. The result is an MP4 with H.264 video and AAC sound that opens in ordinary players and on sites that take video files. Nothing is uploaded and there is no watermark.

How to convert MP3 to MP4

1. Drop your MP3 on Drop an MP3 here, or click to choose. A picture can go in at the same time. You can also add more sound with Add more sound.
2. Check the preview. If the MP3 had cover art, it is already the picture. Use Choose a picture to swap it, or Remove to drop it.
3. Pick a Video look and a Shape. Drag the slider under the preview to see another moment.
4. To use only part of the sound, set Start at (s) and End at (s). Tick Fade the sound out at the end for a soft finish.
5. Press Make the video, then Download the MP4.

The three looks

Waveform videos are limited to 12 minutes here, because every frame is drawn in your browser. Picture only has no such limit. For a longer track with a waveform, set End at (s) to cut it into parts.

Choosing a shape

Wide suits players that show video in a wide frame, and tall suits phone-first feeds. Each site has its own limits for length and file size, so check the current ones on the site you are posting to.

Cover art inside the MP3

Many MP3 files carry their cover picture in the tag at the start of the file. The tool reads that tag in your browser and, when it finds a JPEG or a PNG there, uses it as the picture and says so under Picture, with its size in pixels. A small cover looks soft on a 1920 x 1080 frame, so choose the square or tall shape, or swap in a bigger picture with Choose a picture. When the picture and the frame differ in shape, Picture only fills the rest with a blurred, dimmed copy of the picture instead of black bars.

Using only part of the song

Set Start at (s) to 30 and End at (s) to 90 to keep the 60 seconds between them: 90 minus 30. The preview slider moves inside that part. Add Fade the sound out at the end to avoid a hard cut. The fade lasts up to two seconds, or a quarter of the clip when it is shorter than eight seconds.

Worked examples

One song. A four minute MP3 is 240 seconds. The sound in the MP4 is AAC at 192 kbps, which is 192,000 bits a second, or 24,000 bytes. Over 240 seconds that is 5,760,000 bytes, about 5.8 MB, and the still picture adds little to it.

An album in one video. Add three MP3 files of 3:30, 4:10 and 2:55. They play in the order listed, so the video lasts 210 + 250 + 175 = 635 seconds, which is 10:35. Use the arrow buttons to move a file up or down.

Is it the same quality as the MP3?

Not exactly. The MP3 is opened and its sound is encoded again as AAC, which is the usual sound format inside an MP4. Both steps are lossy, so the sound is a little different from the original, though at 192 kbps most listeners will not hear it. Keep your MP3 as the master.

Common problems

• No cover art appears. Not every MP3 has any. Add a picture, or use the waveform look.
• It cannot make the video. The browser must be able to encode H.264. Use a current Chrome, Edge or Safari.
• A waveform video is slow. It draws every frame. Choose 15 frames a second, or Smaller under Size, to speed it up.
• The sound is cut at the end. Check End at (s), which is set to the full length when you add a file.

For a simple picture with sound, there is also add audio to image. For podcast clips with a title and captions, try the audiogram maker. To join tracks first, use the audio joiner.