How do I figure out if my OS is Mac OS X 32 bit or 64 bit? [duplicate]

To tell if you are running the 32-bit or 64-bit kernel (which matters for some device drivers), launch System Profiler and click on the Software heading in the Contents section.

The line 64-bit Kernel and Extensions will say Yes if you are running the 64-bit kernel and No if you are running the 32-bit kernel.

Note: Mac OS X 10.6 Snow Leopard is the last release that a 32-bit Intel Mac can run, Mac OS X 10.7 Lion and up are, by default, 64-bit. Additionally, System Profiler was renamed to System Information in OS X 10.7.

Run this on the command line:

getconf LONG_BIT

This knowledge base article from Apple should provide you with the correct answer as it depends on how old your MacBook Pro is.

Basically if you have anything newer than an 2008 MacBook you have a 64 bit processor and OS…

Here is the cheat table

Another option is to use sysctl in a shell:

$ sysctl hw.cpu64bit_capable

It’ll show 1 if the CPU is capable of running 64-bit programs and 0 otherwise.