Amazon.com is now selling more Kindle books than paperback books - beating its own prediction that this would happen in the second quarter of 2011.

When in July 2010 Amazon announced that Kindle book sales had surpassed those of hardbacks it anticipated that it might take a further year for Kindle books sales to overtake paperbacks - in fact this has already happened.

In the first four weeks of 2011 for every 100 paperback books Amazon has sold, it has sold 115 Kindle books. During this same time period it has sold three times as many Kindle books as hardcover books. This is across Amazon.com's entire U.S. book business and includes sales of books where there is no Kindle edition. Free Kindle books are excluded and if included would make the numbers even higher.

Based on an analysis of searches, Hitwise Intelligence has compiled the following list of Top 10 e-books:

Unsurprisingly Harry Potter comes top of the list and the Bible is also included. The one that surprises me is that Collins Complete Photography Course is at number 4 when theKindle edition is currently 10% more expensive than the hardback edition and its color photos wouldn't reproduce well on the Kindle. But the list is compiled from searches and not sales figures.

Amazon still hasn't disclosed sales figures for the Kindle device, claiming only that  "millions of third-generation Kindle devices with the new advanced paper-like Pearl e-ink display (were sold) in the fourth quarter" and became "the bestselling product in Amazon's history".

Amazon does like to talk of "millions" without giving us firm figures! 

Related articles:

Expanding E-book Market

Kindle outsells hardbacks

eReaders good for books?

Kindle's record sales