These three formats get recommended interchangeably online, which causes more confusion than it should. They're not different "qualities" of the same thing - they're built for different jobs, and picking the wrong one means either wasting storage space or losing quality you can't get back.
The Core Difference: Lossy vs Lossless
- MP3 is lossy - it permanently discards audio data (mostly frequencies humans don't hear well) to shrink file size. A typical song at 320kbps is roughly a tenth the size of the uncompressed original.
- WAV is uncompressed - it stores the raw audio waveform with no compression at all. Files are large, but nothing is discarded or altered.
- FLAC is lossless compressed - it shrinks file size (typically 40–60% smaller than WAV) using compression that can be perfectly reversed, so the decompressed audio is bit-for-bit identical to the source. No data is discarded.
The practical takeaway: WAV and FLAC sound identical to each other (and to the master they came from) because neither one discards anything - FLAC just stores that same information more efficiently. MP3 is the only one of the three where you're trading audio data for file size.
When Each Format Actually Makes Sense
MP3 - everyday listening, podcasts, streaming, anything going on a phone with limited storage. At 192kbps and above, most listeners can't reliably distinguish MP3 from lossless on typical headphones. Below 128kbps, the compression artifacts become audible, especially in cymbals, applause, and complex mixes.
WAV - audio editing and production. Most DAWs (Digital Audio Workstations) default to WAV because uncompressed audio is faster to read/write during editing and avoids any risk of compounding lossy artifacts across multiple edit passes. It's also the standard format for CD audio.
FLAC - archiving and serious listening. If you're keeping a permanent copy of a recording and want it to stay lossless without WAV's file size, FLAC is the better default - same audio quality, less disk space, and metadata (tags, album art) is supported better than in plain WAV.
Converting Between Them
- MP3 to WAV: you get an uncompressed file, but the quality is still whatever the MP3 already had - converting to WAV doesn't restore data the MP3 discarded. Useful for compatibility with software that requires WAV input, not for "upgrading" quality.
- WAV to FLAC: genuinely lossless - ideal if you have WAV masters you want to archive at a smaller file size with zero quality trade-off.
- FLAC to MP3: the common case for "I have a lossless library but need smaller files for my phone." Going lossless → lossy at 256–320kbps is the right move here.
- FLAC to WAV: occasionally needed for older software or hardware that doesn't read FLAC. No quality difference either way since both are lossless.
A Quick Way to Decide
If you're not sure which format you need: ask whether you're listening (MP3 is fine, often preferable for storage), editing (use WAV during the edit), or archiving (use FLAC). Converting between any of these takes seconds with RunConvert's audio converter - upload the file, pick the output format, and the original is deleted automatically once the conversion completes.