How many cycles are in crest to crest?

The number of cycles in a crest-to-crest measurement refers to the number of complete waveforms that fit within that distance. Since one complete cycle consists of one crest and one trough, the number of cycles is equal to the distance from one crest to the next divided by the wavelength. For example, if the distance from crest to crest is equal to two wavelengths, then there are two cycles in that span.