Audio Converter

How to convert audio files

1. Press Add audio files or drop files on the page.
2. Choose the output format. For MP3, pick a bitrate; 192 kbps is a good default for music.
3. Optionally switch to mono or to 44.1 or 48 kHz. Keep as is leaves the sample rate alone where the format allows it.
4. Press Convert. Each file shows its progress, then a Download button.
5. Download the files one by one, or all together with Download all as ZIP.

Which bitrate should I pick?

For comparison, Spotify's Very high quality setting streams at about 320 kbps, songs bought on the iTunes Store come as 256 kbps AAC, and Apple recommends 128 to 256 kbps for stereo MP3 podcasts. The M4A option here encodes AAC at 192 kbps (128 kbps for mono). Sizes in the table use 1 MB = 1,000,000 bytes.

Lossy to lossy: what converting can't do

MP3 and AAC are lossy formats: to make files small, the encoder throws away detail it expects you won't notice, and no converter can bring it back. Converting a 128 kbps MP3 to 320 kbps gives you a bigger file that sounds the same as the 128 kbps one, or very slightly worse, because each lossy encode adds its own small errors.

So convert from the best source you have. If you have the WAV, FLAC or original recording, start from that. Converting MP3 to WAV still makes sense when an editor or device needs WAV; it won't improve the sound, but it won't lose anything more either. The same goes for channels and sample rate: stereo to mono and 48 kHz to 44.1 kHz remove information that converting back later can't restore.

Which files can it open?

The converter uses your browser's own audio decoder (the Web Audio API's decodeAudioData), so the formats it can open depend on the browser. MP3, WAV, M4A (AAC) and FLAC open in all current major browsers. Support for Ogg Vorbis, Opus and WebM audio varies, especially in Safari. WMA files and DRM-protected downloads, such as songs saved in the Apple Music or Spotify apps, don't open in any browser. If a file won't open, try another browser or convert it with a desktop app first.

On sample rates: Keep as is uses the file's own rate where the output format allows it. MP3 files here use 32, 44.1 or 48 kHz, so other rates are converted to 44.1 or 48 kHz, and M4A uses 44.1 or 48 kHz. WAV keeps any rate.

Frequently asked questions

Is MP3 or M4A better?

At the same bitrate, AAC (M4A) usually sounds a little better than MP3, and it's the native format on Apple devices. MP3 plays on practically everything, including older car stereos and players. If you're not sure, MP3 at 192 kbps is the safe choice.

Why is there no M4A option?

M4A export uses your browser's built-in AAC encoder through WebCodecs. Firefox and browsers on desktop Linux don't include one, and Safari added it in Safari 26. Chrome and Edge on Windows and macOS support it.

Does converting to a higher bitrate improve the sound?

No. A higher bitrate can't restore detail that an earlier lossy encode removed; it only makes the file bigger. Convert from a lossless original when you can.

Can I convert a video file to MP3?

Sometimes. Some browsers, including Chrome, can decode the audio track of an MP4 or WebM video directly. Add the video like any other file; if it doesn't open, your browser can't read that file's audio.

Is there a file size limit?

There's no hard limit, but each file is decoded into memory before it's converted. Files over 300 MB or longer than about 20 minutes get a warning because they can be slow or fail on phones. Files are converted one at a time to keep memory use down.

Are my files uploaded?

No. Decoding and encoding happen in your browser, and your files never leave your device.

Sources

1. Spotify Support: Audio quality
2. Apple Support: iTunes Plus (256 kbps AAC)
3. Apple Podcasts for Creators: Audio requirements
4. MDN Web Docs: BaseAudioContext.decodeAudioData()
5. MDN Web Docs: WebCodecs codec selection

Your files never leave your device. Everything on this page runs locally in your browser: there's no upload, no account and nothing stored on a server.