Overview
This guide compares MP3 and FLAC across the most important criteria to help you choose the right format for your needs.
MP3 is universally compatible; FLAC is lossless but files are much larger.
Head-to-Head Comparison
Audio Quality
MP3: MP3 loses some audio data through lossy compression.
FLAC: FLAC is lossless - identical quality to the original recording.
Winner: FLAC
File Size
MP3: MP3 files are very small (3-10MB per song).
FLAC: FLAC files are large (20-40MB per song).
Winner: MP3
Compatibility
MP3: MP3 plays on every device ever made.
FLAC: FLAC requires modern players - not supported by iTunes.
Winner: MP3
Streaming
MP3: MP3 is the standard for podcast and radio streaming.
FLAC: FLAC is not supported by most streaming services.
Winner: MP3
Archiving
MP3: MP3 is not ideal for archiving due to quality loss.
FLAC: FLAC is the ideal archive format for lossless audio.
Winner: FLAC
Technical Foundations
MP3 (MPEG-1/2 Audio Layer III) is a lossy perceptual codec: it applies a hybrid filterbank and MDCT transform, then uses a psychoacoustic model to identify sounds masked by louder neighboring frequencies and discards them, permanently removing data the listener is unlikely to perceive.[1] FLAC (Free Lossless Audio Codec) is lossless: it uses linear predictive modeling to estimate each sample from previous ones, then Rice/Golomb-codes the residual error. Decoding reconstructs the original PCM samples bit-for-bit.[3][4]
File Size and Fidelity
Because MP3 discards inaudible and some audible information, it reaches very small files, commonly around a tenth the size of the uncompressed source at typical bitrates.[2] FLAC removes only statistical redundancy, so it cannot match that ratio; it usually compresses audio to roughly half its uncompressed size while remaining an exact copy.[3] FLAC can therefore be transcoded repeatedly without accumulating artifacts, whereas re-encoding MP3 compounds quality loss.
Bitrate and Quality
MP3 quality is governed by bitrate, expressed in kilobits per second, and may be constant or variable. Higher bitrates discard less data; many listeners find MP3 transparent at around 256 kbps.[2] FLAC has no quality setting in the same sense: its compression level affects only file size and encoding speed, not fidelity, because the output is always a perfect reconstruction of the input regardless of the level chosen.[4]
Metadata and Standardization
Both formats support embedded metadata: MP3 commonly uses ID3 tags, while FLAC uses Vorbis comments, each storing artist, album, track, and cover art.[1][3] MP3 was developed within the MPEG standardization process; FLAC is an open, royalty-free format maintained by the Xiph.Org Foundation, with its bitstream format documented and frozen for long-term stability.[4]
Compatibility and Applications
MP3 is the most broadly compatible audio format, decodable on essentially any device, which suits podcasts, streaming, and storage-limited use.[2] FLAC suits archiving, high-fidelity listening, and any workflow that may re-encode the audio later, since it preserves the master exactly; its support, while wide, is less universal than MP3, particularly on older hardware.[4]
Convert Between MP3 and FLAC
Need to convert your files? Use our free online converter.
Convert Files NowFrequently Asked Questions
Can most people hear the difference between MP3 and FLAC?
In blind tests, most people cannot reliably distinguish 320kbps MP3 from FLAC. The difference is very subtle.
Is FLAC worth it for casual listening?
For casual listening on earbuds or phone speakers, MP3 at 256kbps is indistinguishable from FLAC for most people.
Does Spotify use FLAC?
No, Spotify streams at up to 320kbps OGG Vorbis. Tidal and Apple Music offer lossless quality.
Can I play FLAC on iPhone?
iOS 11 and later support FLAC in third-party apps. iTunes and Apple Music do not support FLAC.
What is the best bit rate for MP3?
256kbps or 320kbps for music. 128kbps for podcasts and speech content.