By Gerry Shih

SAN FRANCISCO (Reuters) - Until recently, Justin Bieber was more influential than Barack Obama -- at least in the world of Klout, the controversial Web startup that claims to measure people's online influence using an algorithm.

Not any more.

Klout said on Tuesday it has overhauled its Website and rejigged its algorithms, mostly by pulling in data from Wikipedia entries, to better reflect a person's status in the real world.

The move toward calculating offline influence is a tricky but expected step for a company that divides opinion, and gets tongues wagging, like practically no other in Silicon Valley.

Since 2008, the firm has tagged social media users with a single number, between 1 and 100, intended to measure their influence. The Klout Score, as it is known, is now based on 400 variables, including how many Twitter followers someone has, and how often or likely it is for their Twitter or Facebook posts to get re-circulated.

As well as changing the algorithm, chief executive Joe Fernandez said, Klout also now analyses LinkedIn profiles, so a user who describes themselves as a company "vice president" or other high-level title may find their Klout score boosted.

The overhaul, which began in January, was part of the company's effort to address critics who pointed to Bieber as a prime example of why quantifying online influence was, at best, irrelevant. The teenage pop singer, with his army of 26 million Twitter followers who retweet his every word, had a Klout score that dwarfed that of the U.S. president.

"We heard the common complaint, 'Klout's interesting, but what about people who are influential in the real world?'" Fernandez said one recent morning in his company's cavernous underground office in San Francisco.

But Fernandez has stuck to his belief that personal influence, that intangible currency of social networks, can be crunched into a number.

As a result of the new algorithm -- which takes into account the number of references in a person's Wikipedia page -- President Obama's Klout score has finally topped Beiber's, four years after Klout launched, Fernandez said.

"Barack Obama is hugely important," Fernandez said, deadpan. "He's referenced everywhere, and that gives him a higher score."

The social media analytics company now sucks in 12 billion bits of data every day from social networks including Facebook, Google Plus and Tumblr, up from 1 billion just months ago. As part of the revamp, most users will see a bump in their scores, according to Fernandez.

Klout, which sells insights about Web users to companies, has caught the attention of major advertisers including carmakers such as GM's Chevrolet which want to identify influential people tweeting about cars, and market to them directly.

(Editing by Daniel Magnowski)