Twitter has always been mum on some key stats about its service—like how many people have actually signed up to use it. But at its Chirp conference Wednesday, co-founder Biz Stone finally made public some numbers. He says the site now has 105,779,710 registered users—and is adding 300,000 new users a day. About 60 percent of them are coming from outside the U.S.

Possibly most significantly, Stone says that only a quarter of Twitter’s users access the site via Twitter.com, as opposed to a third-party Twitter client. That matters because so many of the traffic stats that have been released by measurement services have not taken into account outside usage. Stone said Twitter’s own stats come from its internal system (called Bird Brain) as well as Google (NSDQ: GOOG) Analytics.