There are dozens of audio formats, but only a handful matter for everyday use. Choosing the right one comes down to two questions: do you need to save space, and where will the file be played? This guide explains the common formats, the difference between lossy and lossless audio, and which to pick for music, voice recordings, editing and sharing.
The short answer
- For sharing and playing anywhere: MP3.
- For the best quality in a small file: AAC (M4A) or Opus.
- For editing and recording: WAV.
- For archiving music without any loss: FLAC (or ALAC on Apple devices).
Lossy, lossless and uncompressed
Every audio format falls into one of three groups:
| Group | What it means | Formats | Size per minute (stereo) |
|---|---|---|---|
| Uncompressed | The raw sound samples, nothing removed | WAV, AIFF (PCM) | About 10 MB |
| Lossless | Compressed like a ZIP file, decodes back to exactly the original | FLAC, ALAC | About 5–6 MB |
| Lossy | Removes sound you’re unlikely to notice, for much smaller files | MP3, AAC, Opus, Vorbis, WMA | About 1–2.5 MB |
Lossy formats can’t get the removed detail back, and converting one lossy format to another loses a little more each time. That’s why it’s best to keep a lossless or uncompressed original and make lossy copies from it.
The common formats
| Format | Type | Strengths | Watch out for |
|---|---|---|---|
| MP3 | Lossy | Plays on everything | Slightly lower quality than AAC at the same size |
| AAC / M4A | Lossy | Better quality per megabyte; standard on iPhone, YouTube, streaming | Some old players and car stereos don’t support it |
| WAV | Uncompressed | Perfect quality, every editor reads it | Very large files, limited tags |
| AIFF | Uncompressed | Apple’s equivalent of WAV, good tags | Large files, less common on Windows |
| FLAC | Lossless | Perfect quality at about half the size of WAV | Not supported by some Apple apps |
| ALAC | Lossless | Apple’s lossless format, inside M4A | Mainly Apple devices |
| OGG Vorbis | Lossy | Open, royalty-free; common in games | Limited on Apple devices |
| Opus | Lossy | The most efficient for speech and calls; WhatsApp voice notes | Not everywhere outside apps and browsers |
| WMA | Lossy | Older Windows format | Poor support on phones, Mac and browsers |
Which is the highest quality?
Uncompressed (WAV, AIFF) and lossless (FLAC, ALAC) formats are identical in sound: both give back exactly what was recorded. Beyond that, quality depends on the recording itself, measured by sample rate and bit depth. CD quality is 44.1 kHz at 16 bits; “hi-res” audio uses 24 bits and up to 192 kHz. For lossy formats, a higher bitrate means better quality: MP3 at 320 kbps or AAC at 256 kbps is very hard to tell apart from the original.
Choosing by use
| You want to | Choose |
|---|---|
| Share music or audio that plays anywhere | MP3, 192 kbps |
| Save space on an iPhone | AAC (M4A), 256 kbps |
| Send a voice note or record speech | MP3 at 128 kbps, or Opus |
| Edit, mix or transcribe | WAV |
| Archive CDs or downloads with no loss | FLAC (ALAC for Apple Music) |
| Make an iPhone ringtone | M4R (AAC) |
What PCM means
PCM (pulse-code modulation) is how uncompressed digital audio is stored: the sound wave is measured thousands of times per second, and each measurement is saved as a number. WAV and AIFF files almost always contain PCM. It’s the “raw” form every other format is created from and decoded back to.
How to change an audio file’s format
Renaming a file’s extension doesn’t change its format; the audio has to be converted. To convert to MP3 from almost anything, use the MP3 converter. For a specific format, there’s a dedicated converter: WAV to MP3, M4A to MP3, FLAC to MP3, OGG to MP3 or AAC to MP3. To go the other way, for editing, use MP3 to WAV. All of them run in your browser, so files are never uploaded.
Summary
Use MP3 when the file must play anywhere, AAC or Opus for the best quality per megabyte, WAV while you’re editing, and FLAC to keep music perfect for the long term. Convert from the best original you have, and avoid converting between lossy formats more than once.