How many blogs are there on BlogSpot? Google announced in August 2009 that Blogger officially turned 10 years old. They invited users to send stories about what Blogger meant to them over the past decade. The post included four "fun facts" about Blogger but gave no indication of the number of active blogs, or even the overall number including lapsed blogs and invitation-only private blogs. The post talked of 'millions' of blogs on BlogSpot. Tens of millions? Hundreds of millions? Only Google knows for sure and they're not telling.
Tumblr.com was launched in 2007 as a free micro-blogging service. Over 39 million blogs had been created by the end of 2011. For the latest stats see: http://www.tumblr.com/about
WordPress.com is also a very popular hosted blog service. For the latest stats see: http://en.wordpress.com/stats/
Is there any way to calculate the total number of blogs on Blogger? A Google search didn't turn up any reliable estimates. Can it be worked out from number of digits in the blogID? I don't think so. This blog has a 19-digit ID which leaves scope for an astronomical number of blogs — far in excess of the number that can possibly exist. Until sometime in November 2006 the blogID was an 8-digit incrementing counter. A little bit of searching showed it had reached at least 38 million before the new disguised IDs were introduced.