Amazon has announced that it now sells more Kindle ebooks than all print books – that's hardcover and paperback combined – through the Amazon.com site.

Introduced less than four years ago, the Kindle has quickly become Amazon's top selling product, and now digitised books for the reader have become more popular with its customers than their paper and ink fore-runners.

In the UK, we're still a little more attached to the humble tome, with Amazon.co.uk still selling more printed books than ebooks – although the Kindle versions are out-selling hardcover books two to one.

That's including all hardcover books that aren't available on Kindle, and excluding all free Kindle books – Amazon says if these were included, the number would be "even higher".

Kindle love

"This is truly astonishing when you consider that we've been selling hardcover books from Amazon.co.uk for over 13 years and Kindle books for only nine months," said Gordon Willoughby, European Director, Kindle.

If one wanted to play devil's advocate, one could argue that this isn't all that impressive; surely existing Amazon customers are more likely to buy a Kindle and Kindle owners can only buy their ebooks from Amazon, so it's no surprise that Kindle books are doing well - whereas the rest of the world is free to buy their paper books from wherever they fancy and Amazon would never know about it… but that could just be the bitter bibliophile inside us.

Either way it's an impressive feat for such a young format; how long before the UK's Kindle sales over take print altogether?

Amazon.co.uk won't tell us the ratio of Kindle sales to paperback sales, but if it keeps up its aggressive Kindle marketing, we'd wager not long at all.