It was long suspected that he owns multiple T-shirts of the same colour, so that he does not have to worry about what to wear.
Asked if he owns 12 of the same T-shirt, Zuckerberg said it was more like 20.
"I mean, I wear the same thing every day, right?" Zuckerberg was quoted as saying.
His identical T-shirt collection lives in one drawer that he gets to use. "Like men everywhere," he said.
He also spoke about the future of Facebook, his daily routine and his wedding to his college sweetheart.
The Facebook CEO also revealed that Apple's Tim Cook sent him an iPhone 5.
"It's a wonderful device. iPhone is a great platform," Zuckerberg said.
However, during a recent trip to Russia, when Zuckerberg met Russian Prime Minister Dmitry Medvedev, he dropped his hooded top, jeans and trainers ensemble in favour of a dark suit and tie.
Zuckerberg gave Medvedev a symbolic gift: a plain white T-shirt with the prime minister's Facebook page - Facebook.com/Dmitry.Medvedev - emblazoned across the front.