Microsoft has revealed what U.K. and eurozone customers can expect to pay for Windows 10. Those without genuine copies of Windows 7 or 8.1, who are eligible for a free upgrade, or those with copies who don't upgrade within the year will be asked to pay up to use Microsoft's "last great OS."

The U.K. pricing, according to Neowin, will start at £99.99 (around $157), while in eurozone countries the price, according to, will start at €135 (around $151). Currently, Windows 8.1 retails for similar prices, but the company's "Windows 10 on 1 billion devices" strategy also factors in the free upgrade offer in its bid to convince the world to switch.

Redmond caused confusion earlier this week when it suggested customers using the Insider Program beta versions would not be eligible for a free copy. Microsoft has now clarified that users will need to prove eligibility for the free upgrade to opt out of the Insider Program, which involves receiving further Windows 10 betas after launch. Ineligible U.K. and eurozone consumers will need to pay full price to opt out of future betas.

The U.S. pricing, released previously, will come in at somewhere between $119 and $199, depending on which edition is purchased. Windows 10 will launch on July 29, and any eligible users who don't upgrade within a year after launch will lose out on the offer of a free upgrade.