Pop Airplay
Top 40 Mainstream Chart (often also called Mainstream Top 40 or Top 40/CHR) is an airplay chart from Billboard Magazine and is featured in both sister publications Billboard and R&R. It is often mistaken for and confused with the Pop 100 Airplay charts (formerly Top 40 Tracks). Whereas the Top 40 Mainstream charts and Pop 100 Airplay both measure the airplay of songs played on Mainstream stations playing pop-oriented music, the Pop 100 Airplay (like the Hot 100 Airplay) measures airplay based on statistical impressions, while the Top 40 Mainstream chart uses the number of total detections. Arbitron sometimes refers to the format as Pop Contemporary Hit Radio.
Chart critera
There are forty positions on this chart and it is solely based on radio airplay and is a component chart of the Billboard Hot 100. 130 Top 40 Mainstream radio stations are electronically monitored 24 hours a day, seven days a week by Nielsen Broadcast Data Systems. Songs are ranked by a calculation of the total number of spins per week with its "audience impression", which is based upon exact times of airplay and each station's Arbitron listener data.
Songs receiving the greatest growth will receive a "bullet", although there are tracks that will also get bullets if the loss in detections doesn't exceed the percentage of downtime from a monitored station. "Airpower" awards are issued to songs that appear on the top 20 of both the airplay and audience chart for the first time, while the "greatest gainer" award is given to song with the largest increase in detections. A song with six or more spins in its first week is awarded an "airplay add". If a song is tied for the most spins in the same week, the one with the biggest increase that previous week will rank higher, but if both songs show the same amount of spins regardless of detection the song that is being played at more stations is ranked higher. Songs that fall below the top 20 and have been on the chart after 26 weeks are removed and go to recurrent status.
Use In Countdown Shows
From January 9, 1993 up until its last first-run show in January 28, 1995, American Top 40 used this chart as its main source.