Audio Converter
Convert audio between MP3, WAV, OGG/Opus, M4A/AAC and FLAC locally in your browser.
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An audio converter changes a sound file from one format to another, for example turning a bulky WAV recording into a compact MP3, or a lossy MP3 into a FLAC for archiving (though that cannot restore quality already lost). An audio file is a container plus a codec: the container (MP3, WAV, OGG, M4A, FLAC) is the wrapper, and the codec is the algorithm that compresses the sound. Converting re-encodes the audio stream, which is why it is real computation rather than a rename.
Frequently asked questions
Is my audio uploaded to a server?
Which formats can I convert between?
Does converting MP3 to FLAC or WAV improve the quality?
What is the difference between lossy and lossless?
Which format should I choose?
Is there a file size limit?
Does it work offline?
Why is conversion slower than a desktop program?
About Audio Converter
This converter runs entirely inside your browser using a WebAssembly build of FFmpeg, the same engine behind most desktop and server audio tools. Your file is read from your device, processed locally, and handed back as a download. Nothing is ever uploaded, which makes it safe for voice notes, interviews, unreleased music or anything private.
The most common reason to convert is compatibility or size. MP3 plays on absolutely everything and is the safe default. M4A (AAC) gives slightly better quality at the same size and is the Apple-ecosystem standard. OGG with Opus is the most efficient lossy option, superb for speech and small files, though older players may not support it. WAV is uncompressed and lossless, ideal for editing, but large. FLAC is lossless and compressed, the right choice for archiving music without quality loss.
A key point about lossy formats: converting from a lossy source (like MP3) to a lossless one (like WAV or FLAC) does not improve quality. The detail discarded by the first compression is gone for good; you only get a larger file containing the same audio. Lossless formats are worth it only when your source is itself lossless. Because everything runs single-threaded in the browser to stay private and compatible, very long files use more memory and take longer than a desktop app.
How MP3 taught computers to throw sound away
The MP3 format, finalised in the early 1990s by a team at the Fraunhofer Institute, was built on a startling idea: you can delete a large part of an audio signal and most people will not notice. It relies on psychoacoustics, the study of how human hearing actually works. Our ears mask quiet sounds that occur near louder ones in frequency or time, so the encoder simply discards what it predicts you cannot hear, keeping the file small.
That insight reshaped music. MP3 made songs small enough to share over 1990s internet connections, fuelling the rise of file sharing, portable players and ultimately streaming. The famous test track used to tune the encoder was Suzanne Vega's a cappella song Tom's Diner, earning her the nickname the mother of the MP3, because its bare vocal exposed every flaw in the compression.
Modern codecs have refined the same psychoacoustic approach. AAC (used by Apple and YouTube) and Opus (used by most messaging and conferencing apps) achieve better quality at lower bitrates than MP3 ever could, adapting on the fly between music and speech. Yet MP3 endures, not because it is the best, but because it became the universal language of digital audio, supported by every device ever made.