Reading crest factor without fooling yourself

Crest factor is the ratio between peak and RMS, expressed in dB. A higher number means more dynamic range — more headroom between the loudest moments and the average level. A lower number means a more compressed, more limited mix.

The numbers, roughly

• > 12 dB — generous dynamics. Jazz, classical, acoustic.
• 10–12 dB — modern, balanced.
• 8–10 dB — modern loud. Pop, electronic, hip-hop where headroom isn’t the priority.
• 6–8 dB — heavily limited. You’re in EDM master / pop radio territory.
• < 6 dB — pancake. Transients are gone.

These are ranges, not laws. A grindcore master at 5 dB crest is correct. A folk record at 5 dB is broken.

Why this metric lies

Crest factor is a whole-file number. It tells you about the average peak-to-RMS relationship across the entire track. But your perception of “punch” or “dynamics” is local — it’s about how much energy a snare drum has relative to the bar before it, not the average.

That means a track can have a healthy crest factor and still feel dynamically dead, because the dynamics are concentrated in one section.

How MixLab handles this

MixLab’s Analyzer reports the full-file crest factor as a baseline, plus the band-wise dynamics scores so you can see where dynamics have collapsed. The full Analyzer also runs a sliding-window crest measurement (10s window, 1s hop) — the windowed version is what you want for diagnosing local pumping or section-by-section flatness.

Three things people get wrong

1. Treating low crest factor as a problem in isolation. It’s a symptom. The cause is usually a limiter or a heavy bus compressor. Diagnose the cause, not the symptom.
2. Comparing crest across genres. A heavy metal master will always be flatter than a folk track. You’re comparing apples to vinyl.
3. Optimising for crest factor. Don’t. Optimise for the music. Read the crest factor after the mix is right, not before.