Twitter user growth seriously accelerating? A speculative jaunt into the hypothetical

I still opt to have Twitter send me emails whenever someone follows me because I like to check people out, see what’s happening in their world, and follow if warranted – usually through Tweetie2. This morning I went through the evaluation process on a backlog of emails and I did find a couple people I wanted to follow. That’s when I noticed something interesting. In Tweetie when you look at someone’s profile one of the bits you get back is what Twitter user number they are. I have always checked that value not because I care when someone signed up but rather to see if it’s higher than the highest one I’d seen to date – a very loose and ballpark idea of how large Twitter is and how fast it’s growing. So this morning when I went to to check out a profile I saw that they are Twitter user #130,500,XXX. A couple of weeks ago at Chirp during one or more of the keynotes @ev or @dickc said they were at 105M users.

Extrapolating from those numbers I would guess that Twitter added ~25M users in the last two weeks. For the sake of these extremely rough estimates I am going to round down and say they *only* added 20M users in that time period. Assuming no further acceleration or deceleration – which is unrealistic – Twitter is on track to add 40M users per month, or another 320M by the end of the year. Seems high to me considering the 300-400% growth pulled from those numbers, then again Facebook is at about 400M users right now. Just for argument’s sake I am going to assume that this month’s growth was unusual and perhaps aided by things like Chirp and media exposure. So let’s slice that 40M number into a 10-20M range and we would get another 80-160M by year end and a total user base of about ~210-290M at the start of 2011, and hitting that half a billion user number in late 2012 – early 2013. That feels more feasible, especially for a speculative morning jaunt into the hypothetical.