Co-founder of Posterous, Garry Tan tweeted “If Posterous sustains current growth rate through Sept 2013, our user base will exceed the population of the Earth!” Earth population? “That’s preposterous,” replied Paul Moss. No matter how hairy the audacious projection is, let’s use it to take a wild stab at estimating current total Posterous users and its growth rate.

By the way, in case you don’t know what Posterous is, it is a dead simple blogging service (and it seems Michael Arrington is a fan). Since its launch in June 2008, Posterous has mastered the art of incremental improvements and each feature release resulted in even greater simplification of blogging. Some of the fabulous features of Posterous are autopost everywhere, post tagging via email, group blogging, group blog doubled as email list and Posteorus iPhone app.

Now, back to the guessing game. According to the United Nations, the Earth population is expected to reach 7 billion by 2013. I assume there’s more than 100,000 Posterous users, judging from its increasing popularity. Now, with a current total of, say, 125,000 users and a stubbornly consistent 25% month-on-month growth for 49 straight months, Posterous’ user base will exceed the 7 billion mark by September 2013 (see here for the crude calculation). BUT, as Garry Tan indicated in his tweet, it’s an optimistic projection. Not to imply that there won’t be a groundswell of Posterous users, but the projection is sure bursting and brimming with wild flashes of optimism!

Current Posterous population at 125,000 with 25% month-on-month growth, how close to the actuals, Messrs Agarwal and Tan?

UPDATE: I’ve requested Garry Tan for feedback on the estimation, but he can’t comment.

Posterous to Surpass Earth Population by 2013 IF Only.. originally appeared on GreyReview on September 2, 2009.