Crest factor is a parameter of a waveform, such as alternating current or sound, showing the ratio of peak values to the effective value. In other words, crest factor indicates how extreme the peaks are in a waveform.

Crest factor, defined Simply stated, crest factor—sometimes called peak-to-average ratio—is the difference in decibels between the peak and average levels of a signal. In the strictest technical sense, it only applies to steady-state signals like sine, square, saw, or triangle waves.