WAV vs MP3 for Mastering
Updated July 2026 · by Loopin
Short version: master from WAV, never from MP3. The format you feed into mastering decides how much quality you have to work with — and MP3 throws some away before you start. Here’s why.
Lossless vs lossy, in plain terms
A WAV is lossless: it stores the full, uncompressed audio exactly as your mix sounded. An MP3 is lossy: it shrinks the file by permanently discarding audio it judges you won’t miss — mostly subtle high-frequency detail and quiet content masked by louder sounds. That trade-off is fine for casual listening, but it’s the wrong starting point for mastering.
Mastering pushes and shapes the audio — EQ, compression, limiting — and that processing can expose the artefacts an MP3 introduced. Boosting the highs on an MP3, for example, amplifies the swirly compression artefacts that lossy encoding left in the top end.
Why mastering from MP3 hurts
When you master a lossy file, you’re polishing audio that’s already missing detail. The highs can sound brittle or ‘swooshy,’ transients lose bite, and the limiter has less clean signal to work with. You can’t recover what the MP3 encoder threw away — the data is gone for good.
It gets worse with re-encoding. If you master an MP3 and then the platform re-compresses it to stream, you’ve stacked two generations of lossy encoding, and the artefacts compound. Starting from WAV means the only lossy step happens once, at the very end, when the platform encodes your finished master.
What to deliver, and at what quality
Bounce your mix to WAV (or another lossless format like AIFF or FLAC) at your project’s native sample rate — commonly 44.1 or 48 kHz — and at 24-bit depth for the extra headroom. Leave a little room below 0 dBFS on the mix you send to mastering so the chain has space to work; you don’t need to normalise or limit it yourself.
Deliver the master itself as WAV too. Distributors and streaming platforms prefer a lossless master and handle the lossy encoding for each service on their end, so they always start from the cleanest possible source. If you also need an MP3 for a quick preview, make it from the finished WAV master — never the other way around.
Master your WAV for free
Once you’ve bounced a clean WAV, you can finish it without buying software. Drop the file into Loopin’s free online mastering — it works from your lossless audio, balances the tone, controls dynamics and targets streaming loudness, then lets you A/B against the original so you can hear the difference clearly.
Keep the WAV master as your archive and release file. If you want to understand the loudness side of a streaming-ready master, see how loud a master should be. Format first, master second — start lossless and the whole chain sounds better.
Frequently asked questions
Should I master from WAV or MP3?
Always from WAV. WAV is lossless and keeps the full audio, while MP3 permanently discards detail that mastering would then amplify into audible artefacts. Bounce your mix to WAV at 24-bit and master from that.
Can you master an MP3 if that's all you have?
You can, but the result is limited. The MP3 has already lost detail you can't recover, so the master may sound brittle in the highs and lose transient punch. Use the original WAV mix whenever it's available.
What format should the final master be?
Deliver the master as WAV. Distributors and streaming platforms prefer a lossless source and encode the lossy versions for each service themselves, so they always start from the cleanest file. Make any MP3 from the finished WAV.