Audio formats fall into three groups. Uncompressed formats (WAV, AIFF) store every sample as it was recorded. Lossless formats (FLAC, ALAC) pack the same samples into a smaller file and give back exactly the same audio when played. Lossy formats (MP3, AAC in M4A, Ogg Vorbis, Opus) throw away the parts of the sound people are least likely to hear, which makes files five to ten times smaller.
That one distinction, whether anything is thrown away, explains most of what people ask about formats: why a WAV is huge, why a FLAC is "the same as" a WAV, and why converting an MP3 to WAV does not make it sound better.
What lossless audio means
Lossless audio is audio stored so that every bit of the original digital recording can be recovered. A FLAC file is like a ZIP archive for sound: it is smaller than the WAV it came from, but when it is decoded the samples are identical to the original, bit for bit. Nothing about the sound changes; only the file size does.
Two numbers describe a lossless file:
- Sample rate: how many times per second the sound was measured. 44.1 kHz is CD quality and covers everything up to about 22 kHz, beyond the upper limit of human hearing. 48 kHz is the video standard; 96 and 192 kHz are sold as "hi-res".
- Bit depth: how finely each measurement is stored. 16-bit (CD) gives about 96 dB of dynamic range; 24-bit gives more headroom, which matters when recording and mixing more than when listening.
CD-quality stereo is 44,100 samples × 16 bits × 2 channels = 1,411 kbps, about 10 MB per minute as a WAV.
What lossy compression throws away
Lossy encoders such as MP3 and AAC use a model of human hearing. Quiet sounds right next to loud ones in frequency or time are masked and get fewer bits or none; very high frequencies, which most adults barely hear, are often cut off altogether. At 128 kbps an MP3 encoder typically removes everything above about 16 kHz; at 320 kbps it keeps up to about 19 to 20 kHz.
The lost information never comes back. Converting an MP3 to WAV or FLAC produces a big file that sounds exactly like the MP3, which is why a "FLAC" downloaded from a dubious source is often an MP3 in disguise. You can check a file's history with a spectrogram: a sharp ceiling at 16 kHz across the whole song gives a lossy source away (see how to read a spectrogram).
The common formats compared
| Format | Type | Typical size per minute (stereo) | Plays on | Best for |
|---|---|---|---|---|
| WAV | Uncompressed | ~10 MB (CD quality) | Everything | Editing, recording, video editors, samplers |
| AIFF | Uncompressed | ~10 MB | Apple software, most DAWs | The Mac equivalent of WAV |
| FLAC | Lossless | ~5–7 MB | Android, most players, Windows, macOS; iPhone in Files and VLC | Archiving and listening in full quality |
| ALAC (in .m4a) | Lossless | ~5–7 MB | Apple devices, iTunes / Music | Lossless on Apple devices |
| MP3 | Lossy | ~1 MB at 128 kbps, ~2.4 MB at 320 kbps | Everything | Sharing, old devices, car stereos |
| AAC (in .m4a) | Lossy | ~1.2–2 MB at 160–256 kbps | Everything modern; native on iPhone | Listening on phones; sounds better than MP3 at the same bitrate |
| Ogg Vorbis | Lossy | ~1–2.4 MB | Android, browsers, games | Game audio, open-source software |
| Opus (.opus, .ogg) | Lossy | ~0.2–1 MB | Browsers, Android; WhatsApp voice notes | Speech and streaming at low bitrates |
One source of confusion: M4A is a container, not a codec. An .m4a file usually holds AAC (lossy), but it can also hold ALAC (lossless). The same goes for .ogg, which can hold Vorbis or Opus.
WAV vs MP3: what is the difference?
A WAV is the raw recording; an MP3 is a compressed copy that discards some of it. A 320 kbps MP3 is about a quarter of the size of a CD-quality WAV and, in blind tests, most listeners on most equipment cannot tell them apart. At 128 kbps the difference becomes audible on good headphones: cymbals get a swishy edge, reverb tails smear, and the stereo image narrows.
Use WAV when the file will be edited again (every lossy re-save adds more damage) and MP3 when it only needs to be played or sent. Moving between the two takes a few seconds with the WAV to MP3 and MP3 to WAV converters, which run in the browser.
What is a FLAC file, and is it better than MP3?
FLAC (Free Lossless Audio Codec) is the most widely used lossless format. It halves a WAV, keeps every sample, and supports tags and cover art. Compared with MP3 it is more accurate but not always audibly better: the difference between FLAC and a high-bitrate MP3 is small and depends on the music, your ears and your equipment. Where FLAC clearly wins is as a master copy: you can turn a FLAC into any other format later without stacking losses. If a device doesn't play FLAC, convert a copy with FLAC to MP3 or FLAC to WAV and keep the original.
M4A vs MP3
An M4A with AAC is the newer design: at the same bitrate it usually sounds better than MP3, especially below 192 kbps, and it is the native format of iPhones, iTunes and Apple Music. MP3 plays on more old hardware, such as older car stereos and some smart TVs. Voice memos from an iPhone are M4A; if a website or a device refuses them, M4A to MP3 fixes it.
What streaming services use
- Spotify: Ogg Vorbis and AAC up to 320 kbps; since September 2025 Premium also streams lossless FLAC up to 24-bit/44.1 kHz on its apps.
- Apple Music: AAC at 256 kbps, and lossless ALAC up to 24-bit/192 kHz.
- Amazon Music Unlimited, Tidal, Qobuz: lossless FLAC, up to 24-bit/192 kHz on many albums.
- YouTube and YouTube Music: lossy AAC or Opus, up to about 256 kbps for Premium.
Bluetooth headphones re-encode whatever you play into their own lossy codec (SBC, AAC, aptX, LDAC), so lossless streaming only reaches your ears intact over a cable or a lossless-capable connection.
Which format should you use?
| You want to… | Use |
|---|---|
| Edit in a DAW or a video editor | WAV (or AIFF on a Mac) |
| Archive a music collection without losing anything | FLAC (ALAC if you live in Apple's apps) |
| Play on an iPhone or in Apple Music | M4A (AAC, or ALAC for lossless) |
| Play on anything, including old devices | MP3 at 256–320 kbps |
| Send a voice recording or a podcast | MP3 or M4A; Opus if both sides support it |
| Make an iPhone ringtone | M4R (AAC); see how to make a ringtone |
For any pair of formats, the audio converter converts several files at once in the browser, keeps the title and artist tags, and uploads nothing.
FAQ
Is FLAC the same quality as WAV?
Yes. Decoded, a FLAC gives back exactly the samples of the WAV it was made from. It is smaller because it is compressed the way a ZIP file is, not because anything is removed.
Does converting MP3 to FLAC improve quality?
No. It makes a lossless copy of a lossy file: bigger, but it sounds the same as the MP3.
What bitrate is "good enough" for MP3?
256 to 320 kbps is transparent for most people on most equipment. 128 kbps is fine for speech and background listening.
Is 24-bit/192 kHz better than CD quality?
For recording and mixing, the extra headroom helps. For listening, controlled tests rarely find people who can tell a well-made 24/192 file from 16/44.1; the mastering matters far more than the numbers.