According to <a href="https://github.com/blog/841-those-are-some-big-numbers" rel="nofollow">https://github.com/blog/841-those-are-some-big-numbers</a> they have 2 million repositories, getting 4500 new ones every day. But that was 2011.<p>On their about page they say they have +53 Mio projects hosted as of today: <a href="https://github.com/about" rel="nofollow">https://github.com/about</a><p>So, just assume that the average repository is s.th. like 20MB and do the math... sorry, couldn't find the average repository size :P