How to Master a Song in GarageBand (Step-by-Step Guide)

You finished a song in GarageBand, exported it, and played it next to a release on Spotify. It sounds quieter, flatter, somehow smaller. Nothing is wrong with your song: it has not been mastered yet. This guide shows how to master a song in GarageBand step by step, first with the stock plugins, then with a single AU plugin that does the measuring for you.

Why your GarageBand export sounds quiet

GarageBand is built for writing and mixing, not for the final loudness pass. Share > Export Song to Disk writes your mix exactly as it plays, and a raw mix usually sits far below release loudness. Streaming platforms then normalize whatever you upload: Spotify and YouTube play everything at around -14 LUFS, turning loud tracks down but almost never turning quiet ones up. A track exported straight from GarageBand usually lands well under that, so next to a commercial release it simply sounds small.

LUFS is the loudness unit streaming platforms use: it measures perceived loudness over the whole song instead of electrical peaks. Integrated LUFS is the single number to care about, and true peak is the safety ceiling that keeps the file from clipping after MP3 or AAC conversion. Mastering is the pass that brings both to release values without crushing the mix.

What a master actually needs

Whatever tool you use, the job is the same four moves, in this order.

YOUR BOUNCE
    |
[ 1. CLEAN ]  high-pass the rumble, cut the mud (200-400 Hz)
    |
[ 2. EQ    ]  tame harshness (gentle 4-8 kHz dip), open the top
    |
[ 3. COMP  ]  glue, 1-2 dB of gain reduction - no more
    |
[ 4. LIMIT ]  raise loudness to target, true peak ceiling -1 dBTP
    |
RELEASE-READY MASTER

Streaming platforms turn loud tracks down and almost never turn quiet ones up, so mastering louder than the target only costs dynamics. Master for the loudest destination you actually need.

Making music with Suno or Udio instead of recording it? The same numbers apply: there is a step-by-step Suno mastering guide too.

Path 1: master with GarageBand stock plugins

GarageBand on Mac ships everything needed for a serviceable master. It is manual, but free.

1. Show the master track: in the menu bar, Track > Show Master Track. Every mastering plugin goes on this track, not on your instruments.
2. Open the master track's Smart Controls and add Channel EQ as the first plugin. High-pass the sub-rumble around 30 Hz, cut 1-2 dB around 200-400 Hz if the low mids feel muddy, and add a gentle wide dip around 4-8 kHz if the top feels harsh.
3. Add Compressor after the EQ. Aim for 1-2 dB of gain reduction at most, ratio around 2:1, slow attack. If you can hear it working, it is working too hard.
4. Add Limiter last. Set the output level to -1 dB and raise the gain until the song is competitive but not squashed. When the drums stop punching, back off.
5. Turn off Auto Normalize in GarageBand > Settings (or Preferences) > Advanced, so the export keeps your levels.
6. Export with Share > Export Song to Disk, uncompressed WAV or AIFF at the highest quality.

The catch: GarageBand has no LUFS meter, so you cannot verify where the master actually lands. Stock mastering is judged entirely by ear, often on speakers and rooms that hide problems. It works, but it is guesswork with good intentions.

Path 2: one AU plugin on the master track

This is the part Transientik Master was built to remove. It is an AU plugin, so it loads natively in GarageBand: copy the .component file into /Library/Audio/Plug-Ins/Components (or follow the install video on the download page), restart GarageBand, and it shows up under Audio Units.

Put it on the master track and play the song through once so it can analyze the full track (or trigger the analysis manually): it measures what a meter would tell you, builds the chain from the previous section, and shows every decision in a readable log. Deterministic DSP, 100% local: your song never leaves your Mac, and the same input always produces the same master.

The full walkthrough, from an empty master track to the final bounce:

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