Who Knew - Chart Performance

Chart Performance

In the Oceanic region, the song debuted at number six on the Australian Singles Chart. The song then rose and peaked at number two for two consecutive weeks. In total, the song stayed in the charts for thirty-two weeks, becoming Pink's second longest charting single in that country. The song is also the seventy-fifth Best Of All Time single in Australia, and is certified platinum for sales of over 70,000 copies. It was ranked at number nine on ARIA's Top 100 singles of 2006. The song had debuted at number thirty-six on the New Zealand Singles Chart, and eventually rose to number eleven, just missing the top ten. The song spent a total of twelve weeks on the charts.

In the European markets, the song was generally successful. "Who Knew" entered the UK Singles Chart at nineteen in early June, 2006 and ascended to a peak at five the following week. It is her joint fifth highest charting single in the UK and her second longest charting behind only "So What". With a total of 26 weeks inside the top 100 songs it beats her number-one hit "Just Like A Pill". The song had success throughout other charts in Europe, where it peaked in the top twenty in Switzerland, Austria, France, Belgium, Finland and Norway, while it peaked in the top fifty in The Netherlands and Sweden.

When the single was originally released in North America, "Who Knew" was less successful. Though it peaked at number nineteen on the BDS Airplay Chart in Canada, it was virtually ignored by American radio. In the U.S., where it was released to mainstream radio on May 8, 2006, it failed to chart on the Billboard Hot 100, initially reaching number 18 on the Bubbling Under Hot 100 Singles chart (which comprises the most popular songs yet to enter the Hot 100). Billboard magazine credited the poor performance of the single on radio with significantly reducing momentum of initial sales of I'm Not Dead.