Lossless vs Lossy Audio: What's the Difference?
Two words decide most of what you need to know about audio quality and file size. Get them straight and bitrate choices, format choices, and conversions all start making sense.
Lossless: keep everything
Lossless formats store the audio without throwing any of it away. Decode a FLAC or WAV file and you get back exactly what went in, bit for bit. The upside is perfect fidelity and a clean master for archiving or editing. The downside is size — lossless files are large, sometimes 5–10× an equivalent MP3.
Lossy: throw away what you probably won't hear
Lossy formats — MP3, AAC, OGG Vorbis — use psychoacoustic models to discard sound that's hard to perceive, shrinking the file dramatically. At higher bitrates the loss is inaudible to most people, which is why lossy audio runs the world's phones and streaming. But the discarded data is gone permanently.
The one-way street
This is the rule that trips people up: you cannot turn lossy back into lossless. Wrapping an MP3 in a FLAC container produces a bigger file, not a better one — the detail was already thrown out. Real lossless quality only ever comes from a lossless source. (This is the same reason a higher bitrate can't rescue a weak file — see 320 kbps explained.)
What it means for converting to MP3
- Lossless → MP3 (e.g. FLAC or WAV): a clean single encode from a perfect source. Use 320 kbps for the best result.
- Lossy → MP3 (e.g. M4A, AAC, OGG): a lossy-to-lossy step. Stay at 256–320 kbps so you don't pile new artifacts on top of old ones.
So which should you keep?
If you have a lossless master, keep it for archiving and convert copies to MP3 for everyday use. If all you have is a lossy file, just convert at a high bitrate and don't expect more than the source contains. Either way, mp3bat does the encode on your device — your files never leave your browser.
Convert your audio →FAQ
Is MP3 lossless or lossy?
MP3 is lossy — it permanently discards audio data to shrink the file. That data can't be recovered, which is why you can't turn an MP3 back into a true lossless file.
Can you convert lossy back to lossless?
Not meaningfully. You can save an MP3 into a FLAC or WAV container, but the discarded detail is gone for good — the result is a larger file with no extra quality. Lossless quality only comes from a lossless source.
Should I convert FLAC to MP3?
For everyday listening on phones and players, yes — MP3 at 320 kbps is far smaller and sounds excellent. Keep the FLAC as your archive so you can re-encode later if you want.