Before converting audio from one format to another, it helps to understand one thing: a 3-minute WAV weighs around 30 MB, the same audio as MP3 at 192 kbps weighs about 4 MB, and Opus can drop below 2 MB with similar perceived quality. The difference isn't magic, it's codec choice. Picking the wrong output format means either wasting space or losing quality you didn't need to lose.
Lossy vs lossless
Audio codecs split into two families:
- Lossless: WAV and FLAC. They store the full waveform or compress it without discarding any data — decompressing a FLAC gives you back exactly the same samples as the original. WAV doesn't even compress, it's raw PCM signal.
- Lossy: MP3, AAC (M4A), OGG Vorbis and Opus. They discard information the human ear barely perceives (frequencies masked by louder ones, for example) to achieve much smaller sizes.
The key rule: converting from a lossy format to a lossless one doesn't recover the quality that was lost. An MP3 converted to FLAC still sounds like an MP3, it just weighs more now. The loss happens once, at the first lossy compression, and is irreversible.
Bitrate: only matters for lossy formats
Bitrate (128, 192, 256 or 320 kbps) controls how much data per second the lossy codec uses to represent the audio. More bitrate means more fidelity and more weight. For WAV and FLAC, a bitrate control doesn't make sense — they're lossless, so size is determined by duration and signal complexity, not a number you pick.
Quick reference:
- 128 kbps: acceptable for speech, noticeable quality loss on dense music.
- 192 kbps: a good balance for most uses.
- 256-320 kbps: practically indistinguishable from the original for most ears.
Which format to pick for each case
- Editing or archiving the original audio: FLAC. It compresses to half or less of WAV's size with zero loss, and you can go back to it as many times as you want without accumulated degradation.
- Distributing or sharing it (podcast, music, voice): MP3 if you need universal compatibility, Opus if the destination supports it (it's more efficient than MP3 at the same bitrate, ideal for streaming and VoIP).
- Processing it further with other tools: WAV. Every time you reopen and resave a lossy format, you lose additional quality (generation after generation); WAV avoids that while you're editing.
- M4A (AAC): a good choice for Apple devices or when you want better quality than MP3 at the same bitrate.
Frequently asked questions
Does converting MP3 to FLAC improve quality? No. The file will be larger but sound exactly the same (or worse, never better) than the original MP3.
Which format is smallest while keeping good quality? Opus, especially at low-to-medium bitrates (64-128 kbps), is the most efficient of the modern lossy formats.
Is my audio uploaded to a server to convert it? No, the whole process runs in your browser with FFmpeg compiled to WebAssembly.
Is there a file size limit? No, the real limit is your own device's memory and processing power.
Convert your audio for free between MP3, WAV, OGG, FLAC, M4A and Opus with the audio converter, with bitrate control and 100% in your browser.