Billboard publishes a number of other charts that address the popularity of particular pop recordings. The most important of these is the Mainstream Top 40 radio airplay chart. Billboard's radio airplay charts are not published in the regular release of Billboard magazine. They are part of a separate publication called Billboard Radio Monitor. The Mainstream Top 40 chart ranks songs played on radio stations specifically identified as using a mainstream top 40 format by the number of times they are played during a given week. Billboard also provides a figure of the number of people reached by a particular song based on the audience size of the reporting stations. However, the number of people reached does not affect the chart ranking
Other relevant pop music charts published by Billboard include Hot Videoclips and Hot Ringtones. It is possible that data from either or both of these could be used in the future to determine song popularity on the Hot 100.
