Microsoft's Lumia 640 and 640 XL are now on sale, and they're crazy cheap

Low-end Lumia's have long proved popular and there are now two more impressively affordable options to choose from.

Microsoft has confirmed that the Lumia 640 is out now and it will be followed by the Lumia 640 XL by the end of April.

The Lumia 640 has a 5.0-inch 1280 x 720 display, a 1.2GHz quad-core Snapdragon 400 processor, 1GB of RAM, a 2500 mAh battery, an 8MP main camera, a 1MP front-facing snapper, 8GB of storage and a microSD card slot and it starts from just £99.99 SIM-free or £15.50 per month on contract.

The Lumia 640 XL has a larger 5.7-inch 1280 x 720 screen, a 1.2GHz quad-core Snapdragon 400 processor, 1GB of RAM, a 3000 mAh battery, a 13MP rear camera, a 5MP front-facing one, 8GB of storage and a microSD card slot and starts from £219 SIM-free.

Piling on the extras

That makes both phones pretty good value, especially the basic Lumia 640. But there's even more value than meets the eye, as they both include a one year Office 365 personal subscription worth £59.99, which grants you 1TB of OneDrive storage.

They also both support 4G and run Windows Phone 8.1, with the promise of an upgrade to Windows 10 Mobile when it becomes available.

Both phones are single-SIM and will be available on contract from a range of retailers and in a variety of colours, including glossy cyan, white and orange and matte black for the Lumia 640, or matte cyan, orange, white and black or glossy white for the Lumia 640 XL.

The world of low-cost smartphones is getting ever more crowded, but with a sub-£100 price tag and high value extras the Lumia 640 could well stand out. At more than double the price the Lumia 640 XL might be a tougher sell, but its larger screen and better camera should certainly help.

• We're still fans of the Nokia Lumia 630.