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Mac OS X: How can I tell if I'm in 64-bit mode?

How do I find out if my 2010 MacBook Air is 64 or 32 bit?

Trying to download Eclipse.

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marked as duplicate by Arjan, Tom Wijsman, Nifle, Sathya Apr 10 '11 at 17:43

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

Wouldn't you also need 64bit Java for 64bit Eclipse? I don't know if Macintosh computers ship with that, so make sure you check that out too. – AndrejaKo Apr 7 '11 at 23:11
You can check this on – Adrien Be May 27 '15 at 16:35
up vote 5 down vote accepted

Goto Apple > About this Mac > More Info > "Select Software" If "64-bit Kernel and Extensions" says Yes you are running 64bit if No 32bit.

If you want to change it see this artical


share|improve this answer, Finder ? Please explain! – Tawani Apr 7 '11 at 23:14
Sorry the Apple in to top left hand corner of your screen. Another way to do it is to simply go in finder to Applications/Utilities/System the click the Software tab in the left hand pane then on the right under System Software Overview you will see 64-bit Kernel and Extensions – yoydigg3r Apr 7 '11 at 23:15
found it. 64 bit - no. Thanks. – Tawani Apr 8 '11 at 0:17
You can run 64-bit applications on a 64-bit machine, even if the kernel is running in 32-bit mode. – Cody Gray Apr 8 '11 at 0:24

It's 64-bit. All of the MacBook Air versions use Core 2 Duo processors, which are 64-bit processors. The kernel won't be running in 64-bit mode (as @Mathew's answer showed you how to find out), but that in no way limits you to 32-bit apps. OS X can run each program in a different mode, and tries to run each program in the best possible mode -- many programs come with both 32- and 64-bit code included, and the OS will automatically pick the best one for your CPU. If you run the Activity Monitor utility, it'll show you what programs are currently running (including invisible background programs), and its "Kind" column will show what mode they're running in -- I'll bet more than half are "Intel (64 bit)".

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