A Beginner's Guide to Audio File Formats

Why the Format You Choose Matters

Every audio file is a container for a stream of numbers — thousands of measurements per second describing how a speaker cone should move. The format decides how those numbers are stored. It might keep every one exactly as recorded, or it might throw away the ones your ears are least likely to notice. That single decision affects file size, compatibility, editing flexibility and, in some cases, how the music sounds after a decade in a dusty folder.

Two questions cut through most of the confusion. First: will this file be edited, mastered or archived? Second: where will it be played, and how much space do you have? If the honest answer is "both", you'll need more than one format. That's normal — most working audio setups use two or three.

Uncompressed Formats: WAV and AIFF

WAV and AIFF store audio as raw pulse-code modulation (PCM) data. Nothing is discarded; the file is essentially a straight digital transcription. WAV is the de facto standard in most studios, and AIFF is its long-standing counterpart, functionally near-identical for most purposes.

The catch is size. A stereo recording at 44.1 kHz and 16-bit — CD quality — runs to roughly 10 MB per minute. Bump that to 24-bit at 96 kHz for a full band and you're near 33 MB per minute. A three-minute song becomes a 100 MB file, and a two-hour multitrack session can eat a terabyte.

So why bother? Because uncompressed files are the safest place to record, edit and mix. Every fade, every pitch correction and every plug-in adds and takes away samples. Start with lossy material and you're stacking artefacts on top of artefacts. Start with a clean PCM file and you have headroom to work.

Lossless Compression: FLAC and ALAC

Lossless formats shrink PCM data without losing a single bit. They work more like a zip file than a photo filter: a clever algorithm spots redundancy in the waveform and encodes it more efficiently. Decode the file and you get back exactly what went in — verifiable, bit for bit.

• FLAC is open, widely supported and typically cuts file size to around 50–60% of the original. A 40 MB WAV might land at 22 MB.
• ALAC, its main rival, achieves similar savings and is the natural pick if your playback gear supports it natively.

Lossless is the sensible default for a music library, a sample archive or any master you intend to keep. You get roughly half the storage cost of WAV with none of the quality compromise — and you can always convert back to WAV later with no penalty.

One caveat: lossless files are still far too heavy for streaming to a phone over mobile data, and some older car stereos and budget players simply won't touch them.

Lossy Compression: MP3, AAC and What You Trade Away

Lossy codecs discard information permanently. They exploit the limits of human hearing — masking effects, where a loud tone hides a quieter one nearby, and the fact that most adults can't perceive much above 16 kHz. Done well, the result is impressively close to the original at a fraction of the size.

• MP3 is the most universally compatible format ever made. At 320 kbps it's hard to fault on casual listening; at 128 kbps, cymbals smear and bass turns mushy.
• AAC generally sounds better than MP3 at the same bitrate and is the default for most streaming services. Bitrates of 96–128 kbps are common and often perfectly acceptable on earbuds.
• Ogg Vorbis and Opus are modern open alternatives. Opus in particular is excellent for speech and low-latency calls.

The golden rule: never transcode a lossy file into another lossy format. Converting a 128 kbps MP3 to 320 kbps AAC doesn't restore anything — it just re-encodes the damage and makes the file bigger. Always go back to a lossless or uncompressed source if you can.

Bit Depth, Sample Rate and Bitrate Explained

These three numbers cause most of the confusion, so here's the plain version.

• Sample rate is how many times per second the waveform is measured, in kHz. 44.1 kHz is CD standard, 48 kHz is standard for video and broadcast, and 96 kHz and above are used for high-resolution work and heavy processing.
• Bit depth is the precision of each measurement. 16-bit gives about 96 dB of dynamic range, fine for delivery. 24-bit gives around 144 dB, which matters when recording quiet sources or stacking many tracks.
• Bitrate only applies to lossy files. It's the data used per second, in kbps. Higher means less discarded, up to a point of diminishing returns.

For most home recording, 24-bit at 48 kHz is a sweet spot — plenty of headroom, manageable file sizes. For final delivery to streaming, 16-bit at 44.1 kHz is perfectly respectable.

Choosing a Format for the Job

A practical setup looks something like this:

• Recording and editing: WAV or AIFF, 24-bit, 48 kHz or 96 kHz.
• Archive and personal library: FLAC, or another lossless codec your gear supports natively.
• Streaming and sharing: AAC at 256 kbps or higher, or MP3 at 320 kbps for maximum compatibility.
• Podcasts and spoken word: MP3 at 96–128 kbps mono, or Opus if your platform handles it.
• Sound effects and samples: keep the originals lossless, then export copies as WAV for use in a project.

Storage is cheap and getting cheaper, so there's little reason to keep your only copy of anything in a lossy format. Keep the master, export the delivery file, and let each format do the job it's good at. Once you've settled into that rhythm, format choices stop being a worry and become just another routine part of the workflow.