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A change to the rules of the US singles chart has sent Harlem Shake to No 1. Baauer's YouTube smash is the first beneficiary of a policy that allows viral sensations to become hit records.

As of this week, YouTube views are one of three metrics used to calculate the Hot 100 at Billboard magazine – America's most important singles chart. Alongside sales and radio play, officials will monitor views of official music videos, as well as "user-generated clips that utilise authorised audio". Streaming audio services such as Spotify and Rdio have been part of the rankings since late last year.

Without the help of Harlem Shake's 103m YouTube views (most of which come from fan-created tribute videos), Baauer would only have placed within the Hot 100's top 15, according to Billboard's Bill Werde. The Brooklyn producer sold 262,000 copies of the song; compare this to Macklemore & Ryan Lewis's Thrift Shop, which sold 412,000 but only reached at No 2. "The very definition of what it means to have a hit is ever-changing," Werde said. "When the charts launched more than 70 years ago, a hit was defined as selling copies of a single or generating airplay … [Now] a song can be a massive hit on YouTube alone."

The change to Billboard's policies follows two years of discussions with YouTube, Werde told the New York Times. But it was Harlem Shake's massive success that led them to "move forward" with their plans. Suddenly an obscure dance track, released for free last May, was soundtracking more than 4,000 YouTube videos. And Baauer isn't the only artist to benefit from this week's Hot 100 change: Psy's Gangnam Style, last year's million-dollar meme, jumped from 48 to 26 under the new rules.

In the UK, the official singles chart is still based on pounds and pence. If a song was purchased – either on CD, 7in or digitally – it inches toward the top spot. If someone just watched the video on YouTube – it's not going anywhere. The only exception is the Official Streaming Chart, launched last May, which calculates rankings based on data from sites such as Spotify and We7. Baauer is currently at No 56 in the UK.