Understanding Audio File Formats: WAV, FLAC, MP3, AAC, and When to Use Each
Not all audio files are created equal. Here's what actually happens to your music when you export, convert, and upload — and why it matters.
TL;DR
WAV for production and masters, FLAC for archiving and audiophile distribution, MP3/AAC for streaming and sharing. Always work in the highest quality and only convert down for final delivery. The format you choose affects how your music sounds to listeners.
Lossless vs Lossy: The Fundamental Difference
Audio formats fall into two categories: lossless and lossy. Lossless formats (WAV, AIFF, FLAC) preserve every bit of audio data from your recording — nothing is thrown away. Lossy formats (MP3, AAC, OGG) permanently remove audio information to reduce file size, using psychoacoustic models to discard sounds the algorithm decides you're less likely to hear.
The key word is 'permanently.' When you convert a WAV to MP3, data is deleted forever. Converting that MP3 back to WAV doesn't restore the lost data — you just get a larger file with the same reduced quality. This is why you should always keep lossless master files and only create lossy versions for distribution.
In practical terms: a 3-minute WAV file is about 30MB, a FLAC version is about 15-20MB, and an MP3 at 320kbps is about 7MB. The space savings of lossy formats are significant, which is why streaming platforms use them. But for your masters and production files, lossless is non-negotiable.
WAV and AIFF: The Production Standards
WAV (Waveform Audio File Format) is the universal standard for audio production. It's uncompressed, universally compatible, and what you should use for all recording, mixing, and mastering. When you export stems, bounces, or masters from your DAW, WAV is the default for good reason.
AIFF (Audio Interchange File Format) is Apple's equivalent to WAV. Sonically identical, slightly better metadata support, but less universally compatible on non-Apple systems. If you're in an all-Apple workflow, AIFF is fine. Otherwise, stick with WAV for maximum compatibility.
Bit depth matters: 16-bit WAV gives you 96dB of dynamic range (CD quality), while 24-bit gives you 144dB (professional standard). For production work, always use 24-bit. For final masters destined for CD or streaming, 16-bit/44.1kHz is the standard delivery format. Your mastering engineer or distribution service will handle this conversion.
FLAC: The Smart Middle Ground
FLAC (Free Lossless Audio Codec) is lossless compression — it reduces file size by about 40-60% without losing any audio data. Think of it like a ZIP file for audio. The original WAV can be perfectly reconstructed from a FLAC file, bit for bit.
FLAC has become the standard for digital music purchases on platforms like Bandcamp, Qobuz, and Tidal's lossless tier. It's also increasingly supported by streaming platforms as they move toward higher quality tiers. Apple Music uses ALAC (Apple Lossless), which is functionally equivalent.
For archiving your music, FLAC is ideal. It preserves full quality while taking up significantly less storage space than WAV. If you have a back catalogue of masters sitting on a hard drive, converting them to FLAC for archival saves space without sacrificing a single bit of audio quality.
MP3 and AAC: The Everyday Formats
MP3 at 320kbps is transparent to the vast majority of listeners on normal playback equipment. Multiple blind tests have shown that most people — including trained audio professionals — cannot reliably distinguish 320kbps MP3 from lossless audio on consumer headphones or speakers. This is fine for sharing demos, sending to collaborators, or uploading to platforms that re-encode anyway.
AAC (Advanced Audio Coding) is technically superior to MP3 at the same bitrate, which is why Apple and YouTube use it. At 256kbps AAC (Apple Music's standard streaming quality), the audio is excellent and virtually indistinguishable from lossless for most listeners and playback systems.
Spotify uses OGG Vorbis at up to 320kbps on premium, and about 128kbps on free tier. YouTube streams audio in AAC at various bitrates depending on video quality. Understanding what each platform does to your audio helps explain why your mastering engineer's references matter — your music will be heard in multiple formats and you need it to translate across all of them.
Practical Rules for Artists
Rule one: always record and produce in WAV at 24-bit. Every. Single. Time. There is no reason to record in any other format.
Rule two: deliver masters to your distributor in WAV format, 16-bit/44.1kHz unless they specify otherwise. Your distributor will encode to whatever formats each streaming platform requires. Never upload an MP3 to a distribution service — it'll be re-encoded, losing even more quality.
Rule three: keep a FLAC backup of every master. Hard drives fail, cloud services can be lost, and having a lossless archive of your work is just good practice. A 1TB external drive costs about £40 and will hold thousands of FLAC files.
Rule four: use MP3 320kbps for sharing — sending tracks to collaborators, uploading to SoundCloud, or attaching to emails. It's small enough to send easily while maintaining quality that represents your music fairly. Never send a 30MB WAV file in an email when a 7MB MP3 does the job.