Microsoft revealed today that the company has sold 40 million licences of Windows 8 to date. Tami Reller, the Windows Chief Marketing and Financial Officer, revealed the figure during a speech at Credit Suisse 2012 Annual Technology Conference. The sales numbers come shortly after Microsoft revealed it had sold four million upgrade copies of Windows 8 in the first few days of sales in October. Microsoft claims "Windows 8 is outpacing Windows 7 in terms of upgrades."

Recent reports have suggested that Windows 8 PC sales are "well below Microsoft's internal projections," but these latest figures appear to suggest that Windows 8 licences are fairing ok. Promotions on Windows 8 upgrade copies appear to be helping along early sales. In comparison, Microsoft sold 60 million licences of Windows 7 after just over two months of sales. Microsoft did not discuss Microsoft's Windows RT sales or any figures for the company's recently launched Surface RT tablet.