How can I check the bitness of my OS using Java? (J2SE, not os.arch)


I'm developing a software application that checks what kind of software you have installed, but in order to do so, I must know if the OS is a 32 bit or a 64 bit OS.

I tried System.getProperty("os.arch"); but then I read that this command only shows us the bitness of the JDK/JRE, not the OS itself. If you could tell me how to know which OS is being used (Windows 7, Mac OS, Ubuntu, etc...) that would be simply awesome.


Should be available on all platforms, see the Java System Properties Tutorial for more information.

But 64 bit Windows platforms will lie to the JVM if it is a 32 bit JVM. Actually 64 bit Windows will lie to any 32 bit process about the environment to help old 32 bit programs work properly on a 64 bit OS. Read the MSDN article about WOW64 for more information.

As a result of WOW64, a 32 bit JVM calling System.getProperty("os.arch") will return "x86". If you want to get the real architecture of the underlying OS on Windows, use the following logic:

String arch = System.getenv("PROCESSOR_ARCHITECTURE");
String wow64Arch = System.getenv("PROCESSOR_ARCHITEW6432");

String realArch = arch != null && arch.endsWith("64")
                  || wow64Arch != null && wow64Arch.endsWith("64")
                      ? "64" : "32";

See also:

HOWTO: Detect Process Bitness

Why %processor_architecture% always returns x86 instead of AMD64

Detect whether current Windows version is 32 bit or 64 bit