Windows memory requirements

Here are the memory requirements for different versions of Windows:

Windows version	Minimum memory required
Windows 2008, 2008 R2	512 MB minimum 2 GB or more is recommended
Windows 2012, 2012 R2	512 MB minimum
Windows 7, 8, 8.1, 10	2 GB minimum for 64-bit systems

References:

http://windows.microsoft.com/en-us/windows7/products/system-requirements

http://windows.microsoft.com/en-US/windows-8/system-requirements

http://www.microsoft.com/en-us/windows/windows-10-specifications

https://technet.microsoft.com/en-us/windowsserver/bb414778.aspx

https://technet.microsoft.com/en-us/library/dn303418.aspx