Lossless vs Lossy Audio: What's the Difference?
Learn the difference between WAV, FLAC, MP3 and other audio formats, and why making an MP3 into FLAC does not restore quality.
Lossless audio keeps all of the audio information it is given. Lossy audio removes some information to make a much smaller file. That is why FLAC is good for keeping a master and MP3 is good for sending or listening on almost anything.
The one rule worth remembering is this: converting an MP3 to FLAC does not bring the missing quality back. Keep the best original and make new listening copies from that.
Which one do you actually need?
Use WAV, AIFF, FLAC or ALAC when the file will be edited, archived or used to make more versions later. Use MP3, AAC or Opus when small size and easy playback matter more than keeping every last bit of the source.
WAV and AIFF are normally uncompressed, so they are very large. FLAC and ALAC are compressed without losing information, which makes them useful for storage. MP3 and AAC get much smaller by discarding information.
A simple master-and-copy workflow
Find the best source
Use the original recording, CD rip or lossless export if you have it. Do not start from an old MP3 when a better source exists.
Keep one lossless master
Use the original format or make a WAV, AIFF, FLAC or ALAC master that your tools can open.
Make the listening copy from the master
Choose MP3, AAC or another required delivery format. Do this once from the best source.
Name the files clearly
Include words such as master, edit, web or mp3 so you do not accidentally use a delivery copy as the source next time.
Common problems
The FLAC is larger but sounds no better
It was made from an MP3 or another lossy source.
Find the original lossless source if one exists.
Repeated copies sound brittle
A lossy file was converted to another lossy file several times.
Return to the lossless master for every delivery version.
An editor rejects FLAC
That editor expects uncompressed PCM audio.
Make a WAV working copy and keep FLAC for storage.
Frequently asked questions
Can everyone hear the difference?
Not always. Codec, bitrate, music, equipment and the listener all matter. Lossless is still useful for future editing.
Is FLAC always better than MP3?
It is a better master when the source is lossless. MP3 is often a better small delivery file.
Does MP3 to WAV improve quality?
No. It creates an editable uncompressed file from the MP3, but it cannot restore removed detail.
What should I archive?
Keep the original and, when useful, a widely supported lossless copy.
Extra: Why MP3 to FLAC cannot restore quality
When an MP3 was created, some information was removed. FLAC can store the decoded MP3 perfectly, but the removed information is no longer there to store.
An MP3-to-FLAC conversion can still help if an editor requires FLAC or if you want to edit without adding another lossy save. Just do not mistake the larger file for a better source.
