Methods and apparatus to identify and credit media using ratios of media characteristics are disclosed herein. Example methods and apparatus determine a first ratio based on a first combination of time intervals of a monitored media signature, the monitored media signature including a plurality of time intervals, respective ones of the time intervals being between respective adjacent characteristics identified in the media, determine a second ratio based on a second combination of time intervals of the monitored media signature, generate a monitored media ratio signature based on the first and second ratios, and compare the monitored media ratio signature with a reference ratio signature to identify the media.