Chart criteria

Songs on the chart are ranked by the total number of spins detected per week. Songs which gain plays or remain flat from the previous week receive a bullet. A song also receives a bullet if its percentage loss in plays does not exceed the percentage of monitored station downtime for the format. If two songs are tied in total plays, the song with the larger increase in plays is placed first.

There are forty positions on this chart and it is solely based on radio airplay. 167 Mainstream Top 40 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 receive a "bullet", although there are tracks that 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 ranks 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.

Since the introduction of the chart until 2005, songs below No. 20 were moved to recurrent after 26 weeks on the chart. In the chart week of December 3, 2005, songs below No. 20 were moved to recurrent after 20 weeks on the chart. Since the issue dated December 4, 2010, songs older than 20 weeks on the chart are moved to recurrent after they drop below No. 15.

Whereas the Top 40 Mainstream and Pop 100 Airplay charts both measured the airplay of songs played on Mainstream stations playing pop-oriented music, the Pop 100 Airplay (like the Hot 100 Airplay) measured airplay based on statistical impressions, while the Top 40 Mainstream chart used the number of total detections.