Startup FanGager has been crunching some numbers to find out who has the most active online fans, as opposed to the most fans. A key distinction. “Brand managers are collecting fans, but we think the conversation should move to engaged fans — just as on the web, counting hits and page views gave way to counting unique users.” CEO Eran Gefen tells Mashable. It measures how many Facebook fans are actually making comments and Liking content. Justin Bieber is top of its chart, but only 359,116 of his 20.4 million Facebook fans are deemed active – 1.8%. That puts him ahead of the Black Eyed Peas (156,422 active fans – 1.1%) and Kesha (150,919 – 1.5%). As for Lady Gaga, only 0.5% of her Facebook fans are active, so despite having more than 29.1 million, it seems only 148,442 of them are actually engaging with the content on her page.