Mark Zuckerberg said that Facebook is adding 5MM global users per week currently. That number is incredibly large, and I want to add some context to this number.
We have a number of social media investments at Union Square Ventures, and when we first invested in each of them, it was pretty early in the size of them. The gross numbers were low but the growth rate was very promising. Around the time of the investment, we talk about goals for the first year. We believe in Big Hairy Audacious Goals (BHAGs) around here, and a typical just-barely-attainable BHAG for an early social media company is to reach 1MM global registered users within 1 year.
So, the best social media startup can strive early on to add 1MM users in a year. By contrast Facebook is adding 52 * 5MM = 260MM users in a year. So, Facebook, despite already being gigantic, can add users 260x faster than some of the fastest growing startups.