The Guardian produces up to 400 pieces of online content a day

"Last year the Guardian had 84 million unique readers every month but its third-party analytics tool only provided traffic data with a four-hour time lag broken down per hour. Most Guardian journalists and editors didn’t even have access to that data. This made life difficult for the newspaper’s digital audience manager, Chris Moran. One of his responsibilities was SEO for 400 pieces of content the Guardian can produce in a day."
Source:  FastCoLabs, 6th February 2014
Note - this will include news stories, blog posts, reviews, and so on, but I'm guessing doesn't include photos.  I'm also assuming that it's a global figure, including the UK, US and other editions