What is music mastering?

Mastering is the last step between a finished mix and a release. It takes the stereo mix you exported and prepares it to be heard everywhere: on earbuds, in a car, on a laptop, on a club system and next to other songs in a playlist.

A good master doesn’t change what the song is. It makes the mix you already made sound finished, consistent and at a level that fits where it will be played.

What a mastering engineer works on

Tonal balance. Small, broad EQ moves fix a mix that is slightly too dark, too bright or too heavy in the low mids. The aim is a track that sounds right on many different speakers, not one that sounds perfect on the speakers it was mixed on.

Dynamics. Gentle compression can glue the mix together and make it feel more even. Too much takes the life out of it. How much is right depends on the genre: a club track and a string quartet need very different amounts.

Stereo image. The width of the mix can be adjusted, and the low end is often kept in the center so it stays solid on mono systems and phone speakers.

Color. Saturation and tape-style processing add harmonics that can make a mix feel warmer or more present. This is a matter of taste, and often left out.

Loudness and peaks. A limiter at the end of the chain raises the overall level and makes sure no peak goes above a set ceiling. This is where the final loudness of the track is decided. How loud should I master for streaming? covers how to choose it.

Consistency across a release. On an EP or album, mastering makes the songs sit together: similar perceived loudness, a related tone, and sensible gaps between tracks.

What mastering can’t fix

Mastering processes the whole mix at once. It can’t turn up only the vocal, take the reverb off only the snare, or fix a part that is out of tune. Any change to the low end affects the kick and the bass together; any change around 3 kHz affects the vocal, the guitars and the hi-hats together.

If something in a single instrument bothers you, fix it in the mix. Mixing vs mastering explains where that line is.

How to prepare a mix for mastering

• Export a stereo file at the session’s sample rate, ideally 24-bit WAV or AIFF.
• Leave headroom: peaks around -6 to -3 dBFS are fine.
• Take any limiter off the master bus that is only there to make the mix loud.
• Check the start and the end for clicks, cut-off tails or long silences.
• Listen once more on a different system, such as headphones or a phone, before you send it.

Online and AI mastering

Online mastering services apply the same kinds of processing automatically. They analyse the mix and choose EQ, compression, stereo and limiter settings for you, then let you adjust the result.

The advantage is speed and cost: you can hear a master in about a minute and try several versions. A human mastering engineer brings judgment and conversation, and will tell you when the mix needs another pass. Many artists use online mastering for demos, singles and releases on a budget, and book an engineer for projects where that conversation matters.

Whichever you use, listen to the result at the same volume as your mix and on more than one system before you release it.

To hear what mastering does to your own song, MasteringKit masters a preview of your mix for free, without an account. Upload a track explains which file to export.

If you have a song ready, master my song walks through the upload, preview and download in three steps. For AI-generated songs, read what mastering can and cannot fix in Suno audio.