MP3 to MP4 Online Free
Convert audio and images into MP4 video. No upload, no watermark, no sign-up.
Combine an MP3, WAV, or voiceover with a cover image to create a video for YouTube, Spotify Canvas, or social media. Everything runs in your browser. No upload, no watermark.
- No upload
- No watermark
- MP3, WAV, M4A
- Ken Burns zoom
- Up to 4K export
How do I convert MP3 to MP4 online for free?
Drop your MP3 and your image into the editor above. Drag the image onto the Main video track, and the MP3 onto the Audio track. Click the right edge of the image on the timeline and stretch it to match the audio length. Finally, click Export to download the MP4 file. It is completely free and no watermark is added.
- Price
- Free, no credits and no watermark
- Account required
- No
- Files uploaded to a server
- No, rendered locally in your browser
- Input
- MP3, WAV, M4A, OGG, FLAC, PNG, JPG, WEBP
- Output
- MP4 (H.264 and AAC) up to 4K
- Aspect ratios
- 16:9 (YouTube), 9:16 (TikTok), 1:1 (Instagram)
- Max export
- 4K at up to 60 fps
- Also does
- Add text, captions, filters, and transitions
Why do you need to convert audio to video?
Many popular platforms do not accept MP3 files directly. If you are a musician wanting to upload a song to YouTube, or a podcaster wanting to publish on video platforms, you must provide an MP4 video file.
The easiest way to satisfy this requirement is to create a "Static Image Video". This means you pair your high-quality audio (MP3) with a single image (like your album cover or podcast logo). The platform gets its video track, and your audience gets to hear your audio. ToolDeck lets you do this instantly in your browser, without needing complex software like Premiere Pro or iMovie.
How to turn audio into video in 4 steps
- 1
1. Import Image & Audio
Drop your MP3/WAV file (Audio) and your cover art (JPG/PNG Image) into the editor. The image will land on the Main Video track, and the audio will land on the Audio track.
- 2
2. Stretch the Image Duration
By default, an image is only 5 seconds long. Drag the right edge of the image block on the timeline to stretch it out. Match it to the exact length of your audio track so the video does not end early.
- 3
3. Add Motion (Ken Burns)
A static image can be boring. Select the image, go to the "Motion" tab in the right panel, and choose "Slow zoom in". This makes the image slowly zoom while the audio plays.
- 4
4. Export as MP4
Open the Export menu, set the resolution to 1080p (or 4K), and click Render. The editor will combine the audio and image into a single MP4 file.
What you get with this converter
Turn Audio into Video
Combine any MP3 or WAV file with a static image (like album art) to create a standard MP4 video for YouTube or social media.
Perfect for Podcasts
Create a visual element for your podcast by using your logo as the background image while the episode plays.
Ken Burns Effect
Make static images feel alive. Add a slow zoom-in or pan effect to your cover art so the video does not feel boring.
Add Text & Captions
Overlay lyrics, quotes, or captions on top of your image. Choose from dozens of fonts and styles.
Export up to 4K
Render high-quality H.264 MP4s at 1080p or 4K, ready to upload to YouTube or Spotify Canvas.
Private by design
No upload step. Your audio, images, and the final MP4 are processed locally using WebCodecs. Perfect for unreleased music.
Who uses an audio-to-video converter?
YouTube Music Uploads
YouTube requires a video track. Turn your unreleased song (MP3) and album cover (JPG) into a 1080p video and upload it.
Podcast Episodes
Upload your podcast audio and use your podcast logo as the background. Add a waveform or text for variety.
Audiobooks
Create chapters for an audiobook by pairing the narration with the chapter title image.
Quotes & Voiceovers
Pair a motivational voiceover with a beautiful background image and add the text as a caption.
Spotify Canvas
Create short 9:16 vertical videos to use as Canvas loops on Spotify by combining a snippet of audio with a moving image.
Lyric Videos
Combine an instrumental track with a solid color background, then add the lyrics as text on the timeline.
What this converter does well, and where it is limited
| Project type | Result | Notes |
|---|---|---|
| Static image + MP3 audio | Works perfectly | The standard use case. Render time is fast, especially for 1080p. |
| Long audio files (1+ hours) | Needs a strong PC | A 2-hour podcast will take a lot of RAM to render as an MP4. Close other tabs. |
| Audio-reactive visualizers | Not supported | We do not have bouncing bars that react to the music. Use the Ken Burns effect on an image instead. |
| Adding subtitles to audio | Works well | Use the AI Captions tool to transcribe the audio, then export them in the video. |
| 4K export with long audio | Very slow | Rendering 4K video for 1 hour takes significant CPU/GPU power. Stick to 1080p for audio-only videos. |
Tips for great audio-only videos
Match the Aspect Ratio
If you are uploading to YouTube, change the project ratio to 16:9 in the Project tab. For TikTok or Reels, use 9:16.
Always add motion
People scroll past static images. Select your image, open the Motion tab, and add a subtle Zoom-in effect to keep the viewer engaged.
Add text for accessibility
If it is a song, add the lyrics as text. If it is a podcast, run AI Captions to display subtitles.
Use high-res images
Since the image will fill the whole screen, use a 1920x1080 (or higher) image so it does not look blurry when exported.
ToolDeck vs Cloud converters
Cloud converters force you to upload your unreleased tracks and images to their servers. ToolDeck renders everything locally, keeping your content 100% private.
| Feature | ToolDeck | Typical cloud converters |
|---|---|---|
| Audio/Images uploaded to a server | Never | Usually yes |
| Watermark on the video | None | Often added |
| Sign-up needed | Not required | Usually |
| Video length limits | None from ToolDeck | Limits on free tier |
| Export resolution | Up to 4K | Usually 720p or 1080p |
| Add text/captions over image | Yes | Varies |
| Works offline | Yes, after page load | No |
MP3 to MP4 FAQ
How it works
How do I convert an MP3 to an MP4 for free?
Drop your MP3 audio and your image into the editor above. Ensure the image is on the Main track and the audio is on the audio track. Stretch the image using its right edge to match the length of the audio. Finally, click Export to download the MP4.
Can I convert audio to video without an image?
Yes, you can set the project background to a solid color (like black or blue) in the Project tab, and just put the audio on the timeline. The video will be a solid color with sound.
Why is my image only 5 seconds long?
By default, images are added for 5 seconds. To make it last for the whole song or podcast, click and drag the right edge of the image on the timeline to stretch it out.
Does the video have a watermark?
No. ToolDeck never adds watermarks to your videos. The export is clean and ready for commercial use.
Formats and Quality
What audio formats are supported?
You can import MP3, WAV, M4A, OGG, and FLAC. The final MP4 will use the standard AAC audio codec.
What is the maximum resolution?
You can export up to 4K (2160p). However, for a static image and audio, 1080p is usually more than enough and renders much faster.
Why is my MP4 file so large?
Video files are larger than audio because they contain many pictures (frames) per second. If the file is too large, try exporting at 720p instead of 1080p.
Privacy
Is my unreleased music safe?
Yes. All rendering happens locally in your browser using WebCodecs. Your MP3 and images are never uploaded to our servers.
Can I use this offline?
After the page loads, the editor works offline. You can turn off your Wi-Fi and still render the MP4.
Your files never leave your device
There is no upload step and no account. The audio, image, and final MP4 are processed entirely in your browser using WebCodecs and WebAssembly. You can verify this by checking your browser's Network tab while rendering.