The Mastering Checklist (Before, During, After)

Published 12 August 2026, 12:00 UTC · updated 26 July 2026, 22:53 UTC · by Loopin

Mastering goes smoothest when you work through it in three stages: before (prep the mix and export right), during (the chain itself), and after (check and deliver). Here’s the whole checklist — balanced mix with about −6 dB headroom, a proper chain that lands near −14 LUFS at −1 dBTP, then A/B against a reference and verify on real devices before you export.

Before: prep the mix

Most mastering problems are actually mix problems that showed up too late. The before stage is about handing the master a clean, well-balanced file with room to work — because mastering acts on the whole mix at once and can’t fix balance issues buried inside it.

Run through this list before you even think about the mastering chain. If anything fails, go back to the mix — it’s far easier to fix there.

Mix is balanced — every instrument and the vocal sit right against each other.
~−6 dB of headroom — peaks around −6 dB, not touching 0 dBFS.
No mix-bus limiter or maximizer on the master fader.
No clipping anywhere in the file — check your peak meter.
Export a 24-bit WAV — not an MP3, not slammed to 0.
Checked in mono and on multiple speakers/headphones for balance and phase.

Why the before stage matters most

Here’s the uncomfortable truth: a great master starts with a good mix. Mastering polishes the whole stereo file — it can’t turn up a buried vocal, tame a boomy bass or move a harsh hi-hat, because those tracks are already glued into one.

Checking in mono catches phase and balance problems that hide in stereo, and listening on more than one system stops you from mastering a mix that only sounds right on your favourite headphones. Get this stage right and the rest is easy.

During: the mastering chain

The during stage is the chain itself, in order. Each step does one job, and the order matters — you correct problems first, then glue, then colour, then handle stereo and loudness last.

You don’t have to build this by hand. An automated tool runs the whole chain for you, but it’s worth knowing what’s happening so you can judge the result.

Corrective EQ — fix any broad tonal imbalance (too dark, too bright, muddy build-up).
Gentle glue compression — a little cohesion so the track feels like one record.
Subtle colour — light EQ character and saturation for warmth and presence.
Stereo — widen tastefully while keeping the low end mono for a solid centre.
Limiter — target about −14 LUFS with a −1 dBTP true-peak ceiling.

After: check and deliver

The after stage is where you catch mistakes before anyone else hears them. The most important habit is A/B’ing against a reference track you love — at matched loudness, so you’re comparing tone and balance, not just which one is louder.

Then confirm your true-peak ceiling, export, and listen on the devices your audience actually uses. A master that sounds great in the studio but falls apart on a phone speaker isn’t finished.

A/B vs a reference track at matched loudness — compare tone, not volume.
Check true peak — −1 dBTP for most platforms, −2 dBTP for Amazon.
Export a WAV — full quality, no lossy compression.
Verify on phone and in the car — the real-world listening test.

Why matched-loudness A/B matters

Our ears equate louder with better. If you A/B your master against a commercial reference and one is even slightly louder, you’ll prefer it — regardless of which actually sounds better. That’s a trap.

Match the loudness of the two tracks before you compare, and suddenly you’re judging what actually matters: tonal balance, width, punch and clarity. This single habit will improve your masters faster than any plugin.

Louder always sounds “better” to untrained ears — remove that bias.
Match levels, then compare tone and dynamics honestly.
Pick a reference in the same genre for a fair comparison.

The true-peak numbers

A true-peak ceiling protects your master from distorting when a streaming platform re-encodes it to a lossy format — the encoding can create peaks slightly higher than the ones you see. A ceiling below 0 dBFS gives that a safety margin.

For most platforms, −1 dBTP is the standard ceiling. Amazon asks for a little more margin at −2 dBTP. Set the ceiling, and let the limiter hold your peaks below it while loudness targets about −14 LUFS.

−1 dBTP — the standard true-peak ceiling for most platforms.
−2 dBTP — a touch more margin for Amazon.
~−14 LUFS integrated — a safe streaming loudness target.

The whole checklist in one workflow

Put it all together and here’s the full run, before to after:

Before: balance the mix, leave ~−6 dB headroom, remove the mix-bus limiter, check mono and multiple speakers, bounce a 24-bit WAV.
Open Loopin’s free online mastering and drop the file in — it runs in your browser, nothing is uploaded.
During: the chain runs corrective EQ, glue, colour, stereo and a limiter to about −14 LUFS at −1 dBTP.
After: A/B Original vs Mastered, and against a reference at matched loudness.
Confirm true peak (−1 dBTP, or −2 for Amazon) and download the WAV.
Verify the finished master on your phone and in the car before you release it.

Run the checklist, free

You don’t need a rack of plugins to work through this. Loopin’s online mastering handles the whole during stage — corrective EQ, multiband compression, saturation, stereo processing and a −1 dBTP limiter with loudness targeting to about −14 LUFS.

It’s free, no signup, no watermark, and nothing you drop in ever leaves your device. Prep your mix, run the chain, check it, and ship a clean WAV.

Frequently asked questions

What should I check before mastering?

That the mix is balanced, has about −6 dB of headroom, no mix-bus limiter, and no clipping, exported as a 24-bit WAV. Also check it in mono and on multiple speakers so balance and phase are solid before you master.

What happens during mastering?

In order: corrective EQ, gentle glue compression, subtle colour, stereo processing (keeping the low end mono), then a limiter that targets about −14 LUFS with a −1 dBTP true-peak ceiling.

What should I do after mastering?

A/B your master against a reference track at matched loudness, check the true peak (−1 dBTP, or −2 dBTP for Amazon), export a WAV, then verify it on your phone and in the car before releasing.

Why match loudness when A/B testing a master?

Louder always sounds “better” to our ears, so an unmatched comparison is biased toward whichever track is louder. Match the levels first and you judge tone, width and punch honestly.

What true-peak ceiling should I use?

−1 dBTP is the standard for most platforms; Amazon prefers a little more margin at −2 dBTP. The ceiling keeps peaks clean after a platform re-encodes your master to a lossy format.