Mastering Compression Settings (Full Guide + Cheat Sheet)

You’ve A/B’d five versions of the same master and every single one sounds smaller, duller, or more pumpy than the mix did before you touched it.

The compressor is doing something. You can see 4 dB of gain reduction. The kick has lost punch.

You pull the threshold back. Now nothing is happening. You push it forward. Now it’s pumping.

The setting that fixes this is almost always ratio, and the mistake is almost always using mix-bus settings (3:1, 6 dB GR) on a master.

Mastering compression is closer to a level-tweaking tool than a sound-shaping one. Different job, different numbers.

This post gives you four field-tested starter kits (transparent, glue, two-stage stacking), a cheat sheet you can bookmark, the right way to pick between VCA, opto, and variable-mu, and the three mistakes that ruin most home masters.

By the end you will know what numbers to reach for the moment you instantiate the comp on the master bus.

TL;DR

Transparent (default): ratio 1.2:1 to 2:1, attack 30 ms, release 150 ms, gain reduction 1–2 dB, soft knee.
Glue (light cohesion): ratio 2:1, attack 30 ms, release tied to tempo (100–200 ms), gain reduction 2–3 dB, soft knee.
Two-stage stacking (most professional masters): first comp at 1.5:1 catching peaks (1–2 dB GR), second comp at 1.2:1 for glue (1 dB GR). Total under 4 dB GR.
Hard ceiling: never exceed 5 dB of static gain reduction on a single mastering comp. If you need more, fix the mix.

What a Mastering Compressor Is Actually Doing

A compressor on the master bus has one job: catch the loudest 1–3 dB of the program material so the limiter that follows can push the whole track louder without the peaks slamming into the ceiling.

That is it.

It is not “shaping the sound.” It is not “adding warmth.” It is not “making the mix glue.”

Those things can happen as a side effect, but they are not the goal. The goal is creating headroom for the limiter to do its work cleanly.

That reframing changes every setting. If you are only catching peaks, the ratio is gentle (1.2:1 to 2:1, never higher than 3:1).

The attack is slow enough to let the transient through (20–50 ms). The gain reduction is small (1–3 dB). The knee is soft so the compression eases in rather than slamming.

Compare this to a mix-bus comp on the drum bus, where 4:1 with 6 dB of GR is normal.

The numbers are different because the job is different. Master bus = level-management. Mix bus = tone-shaping.

Why Less Is More on the Master Bus

Every dB of compression at the master stage is a dB of dynamic range you are giving away permanently.

Unlike a track compressor where you can pull it back if it sounds wrong, mastering compression is the last creative stage before the limiter.

Anything you crush here cannot be recovered.

That is why the settings start gentle.

A 1.5:1 ratio with 1.5 dB of gain reduction will move loudness up by less than half a dB but tighten the macro-dynamics enough that your limiter has 3–4 dB more room to push.

Try the same job with a 4:1 ratio at 4 dB GR and the master sounds smaller, the kick loses snap, and the cymbals start to dip in volume every time the kick hits.

Genre changes the ceiling slightly but not the philosophy.

A loud EDM master can take 2:1 with 3 dB GR and stay alive.

An acoustic or jazz master should rarely exceed 1.5:1 with 1 dB.

A modern hip-hop or pop master sits in the 1.5:1 to 2:1 range with 2 dB GR. The gentle end is always the right starting point.

Want to see how much compression your master actually needs before you set the ratio? Drop the pre-master mix into the Compression Analyzer.

Settings: Ratio, Attack, Release, Gain Reduction

These are the four starter kits.

Pick one based on what you need from the master, not on the genre alone.

1. Transparent (the default)

Use this when the mix is already balanced and you only want to shave the loudest peaks for the limiter.

The ear should not hear the compressor working.

Ratio: 1.2:1 to 2:1
Attack: 30 ms (lets transients through)
Release: 150 ms (auto-release if your comp has it)
Gain reduction: 1–2 dB on the loudest hits
Knee: soft
Best with: VCA-style (SSL G bus comp, FabFilter Pro-C 2 in “Mastering” mode, Cytomic The Glue)

2. Glue (light cohesion)

Use this when the mix sounds like separate parts that need to feel locked together.

Slightly more aggressive than transparent, with the release tied to the song’s tempo so it pulses with the groove.

Ratio: 2:1
Attack: 30 ms
Release: tempo-linked. Faster songs (140+ BPM): 100 ms. Mid-tempo: 150 ms. Slow ballads: 200 ms.
Gain reduction: 2–3 dB
Knee: soft
Best with: variable-mu (Manley Vari-Mu, FairChild 670 emulation, IK T-RackS Vintage Tube Compressor)

3. Aggressive (loud genres only)

Use this only on genres where loudness wins (EDM, modern pop, hip-hop).

Pushes the comp harder so the limiter has even more room. Trades dynamics for level.

Ratio: 2:1 to 3:1
Attack: 20 ms (slightly faster, catches transients more aggressively)
Release: 100 ms (fast, keeps things tight)
Gain reduction: 3–5 dB
Knee: soft
Best with: VCA-style (SSL G, API 2500)

4. Two-stage stacking (the pro move)

Used by most professional mastering engineers.

Two compressors in series, each doing a tiny amount, total under 4 dB. Sounds more transparent than one comp doing 4 dB alone.

Stage 1: ratio 1.5:1, attack 30 ms, release 150 ms, GR 1–2 dB (catches peaks)
Stage 2: ratio 1.2:1, attack 50 ms, release auto, GR 0.5–1 dB (glue)
Combined gain reduction: 2–3 dB total
Best with: VCA + variable-mu combo (e.g. SSL G into Manley Vari-Mu, or FabFilter Pro-C 2 into IK T-RackS)

**Mastering Compression Cheat Sheet:** ratio, attack, release, and gain reduction by goal
Goal	Ratio	Attack	Release	Gain Reduction	Knee
Transparent (default)	1.2:1–2:1	30 ms	150 ms	1–2 dB	soft
Glue	2:1	30 ms	100–200 ms (tempo)	2–3 dB	soft
Aggressive (EDM/pop)	2:1–3:1	20 ms	100 ms	3–5 dB	soft
Stacking, stage 1	1.5:1	30 ms	150 ms	1–2 dB	soft
Stacking, stage 2	1.2:1	50 ms	auto	0.5–1 dB	soft
Hard ceiling	3:1	any	any	5 dB max	soft

When to Stack Two Compressors

The reason most professional masters sound more transparent at the same loudness as a home master is that the engineer is using two gentle compressors instead of one aggressive one.

Each comp moves 1–2 dB. Neither has to work hard. Total reduction stays under 4 dB.

The mechanism: a single comp doing 4 dB at 3:1 has a single, audible release curve.

Listeners can hear it pump. Two comps doing 2 dB each at 1.5:1 produce two overlapping, gentler release curves.

The effect is summed but the artifacts cancel out. The ear reads it as glue rather than compression.

Stack when: the master needs cohesion AND peak control AND you have headroom for two stages.

Skip when: the mix is already cohesive (one transparent comp will do), or you only need 1 dB of GR (one stage is fine), or you are mastering quietly for a non-loudness-driven genre.

Choosing the Right Compressor Type

The compressor model matters more on the master bus than anywhere else in the chain because it is the last shaping stage.

Three families dominate mastering, each with a distinct character.

VCA (SSL G, API 2500, FabFilter Pro-C 2, Cytomic The Glue): fast, clean, surgical. The right choice for transparent peak control and for the first stage of stacked compression. If you only own one mastering comp, make it VCA.

Variable-mu (Manley Vari-Mu, FairChild 670, IK T-RackS Vintage Tube Compressor): slow, warm, glue-y. The ratio is program-dependent (it self-adjusts based on input level). Adds harmonic richness from the tube circuit. Right for genre work where you want the master to feel “produced,” not just loud. Often used as the second stage in a stack.

Opto (LA-2A emulation, Klanghelm MJUC, CLA-2A): smooth, slow, forgiving. Less common on the master bus because the program-dependent release can feel sluggish on full mixes. Better suited for vocals and individual tracks.

Skip on the master unless you specifically want a vintage vibe.

Read Your Track Before Touching the Threshold

1. Measure the crest factor first

Crest factor (peak minus RMS, measured in dB) tells you how dynamic your pre-master mix is.

A mix sitting at 14+ dB crest factor has plenty of room and only needs gentle compression.

A mix at 8 dB or below is already squashed and should not be compressed further at the master stage. See the crest factor explained guide for the full method.

2. Pick a reference track

Load a commercial master in the same genre on a parallel track, level-matched to your master output.

Listen to both back to back.

The reference tells you how much compression your genre actually uses and what the resulting macro-dynamics should sound like.

Without a reference you are guessing.

3. Skip the meter math entirely

If you would rather not measure crest factor manually or guess at the right ratio, drop the pre-master into the Compression Analyzer.

It returns the crest factor, identifies whether the mix is over-compressed or under-compressed, and recommends the ratio, attack, and release that fit the actual file. About 5 seconds per analysis.

Try it on anything: a mix bus, a pre-master, a full master, or a stem. Launch the Compression Analyzer →

3 Common Mistakes on the Master Bus

1. Using mix-bus settings on the master. The most common error. A 4:1 ratio with 4 dB GR works on a drum bus because you want tone-shaping.

On a master bus it kills macro-dynamics, dulls transients, and pushes the kick behind the rest of the kit.

Rule of thumb: if your mastering comp shows more than 3 dB of gain reduction, you are mixing, not mastering.

2. Chasing loudness with the comp instead of the limiter. The compressor is the wrong tool for getting loud.

The limiter is the right tool. If your master is not loud enough, push the limiter, not the comp.

Compression chases loudness only at the cost of dynamic range and transients.

The limiter exchanges the same range for level but in a way that is engineered for it.

3. Compressing without a reference track. You cannot tell if your master is “compressed enough” or “too compressed” in isolation.

Your ears adapt within seconds.

A reference track snaps your perception back to objective. Spotify-loud commercial masters in your genre are the easiest way to calibrate. Without one, you will always over-compress.

Ready to stop guessing? The Compression Analyzer reads your master’s actual crest factor, tells you whether it is under-compressed, balanced, or already squashed, and recommends the ratio, attack, and release that fit your file.

Frequently Asked Questions

What ratio should I use for mastering compression?

Start at 1.5:1 to 2:1 for transparent peak control. Push to 2:1 to 3:1 only on loud genres (EDM, modern pop, hip-hop) where you need 3–5 dB of gain reduction.

Never exceed 3:1 on a single mastering comp. Higher ratios belong on the limiter, not the compressor.

If you need more control, use two stages of gentle compression instead of one aggressive stage.

What attack and release for a transparent master?

Attack 30 ms, release 150 ms. The 30 ms attack lets the transient pass through untouched, then the comp catches the body of the signal.

The 150 ms release is slow enough to avoid pumping but fast enough that the comp is fully recovered before the next downbeat in most genres.

For tempo-driven material, link the release to the song’s BPM (faster songs need faster releases).

How much gain reduction on a master?

1 to 3 dB is the sweet spot for most masters. Loud genres can push to 3–5 dB. Anything over 5 dB of static gain reduction usually means the mix needs more work, not the master.

The exception is two-stage stacking, where each stage moves 1–2 dB and the combined reduction stays under 4 dB but feels more transparent than one stage doing the same total amount.

Should I use one compressor or two on the master?

Two if you need cohesion plus peak control and you have the headroom. Stage one is a fast VCA at 1.5:1 catching peaks. Stage two is a slower variable-mu at 1.2:1 adding glue.

Each does 1–2 dB. The result is more transparent than one comp doing 4 dB alone because the artifacts of two gentle releases overlap and cancel.

One comp is fine when the mix is already cohesive or you only need 1–2 dB of total reduction.

What is the best compressor type for mastering?

VCA is the default, especially for the first or only stage. It is fast, clean, and surgical, which is what peak control needs.

Variable-mu (Manley Vari-Mu, FairChild emulations) is excellent as a second stage for harmonic warmth and program-dependent glue.

Opto compressors (LA-2A style) are usually too slow for the master bus, although they shine on individual tracks.

If you can only own one mastering comp, make it a VCA.

Should compression go before or after the limiter?

Compression goes before the limiter. The compressor catches the loudest 1–3 dB so the limiter has more peak headroom to work with.

A typical mastering chain is: corrective EQ, compressor (or two-stage stacking), tonal EQ, saturation, limiter, and dither.

Reversing the order forces the comp to react to the limiter’s already-flattened output, which produces unpredictable pumping and adds nothing to loudness or quality.

The Bottom Line

Start gentle. Pick transparent (1.5:1, 30 ms, 150 ms, 2 dB) for almost every master. Push to 2:1 with 3 dB GR only on loud genres.

Stack two comps when you need both cohesion and peak control. Never exceed 5 dB of static reduction on a single comp.

Use a VCA for peaks, a variable-mu for glue, and a reference track to calibrate your ears. Compression goes before the limiter, every time.

And if you would rather skip the meter-reading altogether, the Compression Analyzer gives you the number and the settings in about 10 seconds.

If you want to know how compression works, read our complete guide on audio compression. If you want to go further on the rest of the mastering chain, these are worth your time:

Practice and use the numbers as a compass, and you will nail mastering compression faster.

Mastering Compression Settings: A Cheat Sheet for a Transparent Master