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I want to install new software that has these two versions, and I need to know which one to install.

How can I tell the 32 or 64 bit capabilities of my Mac?

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14 Answers 14

25

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.

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153

Run this on the command line:

getconf LONG_BIT
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  • 13
    This is the best answer in my opinion. And a suggestion: put this in your profile: echo "You are on a "$(getconf LONG_BIT)"-bit architecture" Nov 29, 2016 at 22:26
  • This should be marked as accepted rather than following a multi-step process which can be confusing to some. Jan 25 at 2:01
31

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

Apple processors

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20

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.

19

In a terminal window type uname -m. If you get x86_64 then you have 64bit OSx running.

The full output looks something like this:

Darwin Macbook-Air.local 11.4.2 Darwin Kernel Version 11.4.2: Thu Aug 23 16:25:48 PDT 2012; root:xnu-1699.32.7~1/RELEASE_X86_64 x86_64 i386 MacBookAir4,2 Darwin
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11

As you may have seen from all the answers - macs are different than other Operating Systems (OS) in that the 32 bit and 64 bit dividing line is all blurry. You can have 32 bit code run on a 64 bit CPU.

A nice overview of this subject is at Apple's 64-bit Transition Guide Keep in mind, this transition was started before Tiger was released on April 29, 2005 and is effectively complete.

What Is 64-Bit Computing?

For the purposes of this document, 64-bit computing is defined as support for a 64-bit address space—that is, support for concurrent use of more than 4 GB of memory by a single executable program—no more, no less.

Beginning with version 10.4, Mac OS X supports command-line 64-bit executables on G5-based Macintosh computers and 64-bit-capable Intel Macintosh computers.

Beginning with version 10.5, Mac OS X supports full-featured 64-bit applications on G5-based and 64-bit-capable Intel Macintosh computers.

Beginning with Snow Leopard, Mac OS X uses a 64-bit kernel on some Intel computers.

Also - CPU that are "64-bit" still have parts that are only 32 bits wide. Similarly, CPU that are "32-bit" also have parts that are 128 bits (or more) wide. This is why most people focus on the address space for a specific program rather than whether the hardware is "64-bit" or how much of it is "64-bit"

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Go to the Apple Menu and select "About this Mac". If you have a Core Duo processor, you have a 32-bit CPU. Otherwise (Core 2 Duo, Xeon, i3, i5, i7, anything else), you have a 64-bit CPU.

Mac OS X is fairly bitness-agnostic, so either should work. If still in doubt, use the 32-bit version.

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    For completeness, there was also the 32-bt only “Core Solo” processor used in the very first Intel Mac mini (“Early 2006”). Apr 23, 2011 at 4:13
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The arch command with no arguments will display the machine's architecture type.

The results (from the arch(1) manpage):

i386    32-bit intel
ppc     32-bit powerpc
ppc64   64-bit powerpc
x86_64  64-bit intel
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    Uh, no. I have a Core i7 MBP and have the 32-bit kernel enabled since my employer's VPN software requires it, and arch returns i386 for me. My processor is 64-bit and i have lots of 64-bit processes running, though, so this seems to only tell you what the kernel type is.
    – David
    Apr 22, 2011 at 23:42
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    What David said - this only tells you what kernel is running. Like David, I'm using a 32-bit kernel because I need a kext that requires it, but I can run 64-bit user processes with no problem. Apr 23, 2011 at 1:05
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Just run Activity monitor and find the process named kernel_task . Then look at the column Kind. If it says Intel, then you are currently running 32bit mode. If it says Intel (64-bit), then as the text says, you are running 64 bit mode.

Note: You must show All processes, from te dropdown next to the search box (filter).

Then you can check @Nate Bird's answer on what processor you have and the supported modes for it.

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OS X doesn't have an overall 32/64-bit mode; it simply runs each program in the "best" available mode, based on what the CPU's capable of and what the program supports. Many OS X programs come in universal binary format, meaning that they have multiple versions (some combination of PowerPC 32-bit, PowerPC 64-bit, Intel 32-bit, and Intel 64-bit) included in the same file.

Eclipse apparently doesn't come this way, so you have to decide which version to download. I'm not familiar enough with it to know if it has to run in the same mode as what you're trying to debug; if so, run your program, and look for it in Activity Monitor to see what mode it's running in. If Eclipse doesn't have to be in the same mode (or the Java code just runs inside Eclipse), then you can use either one (unless you're on a 32-bit-only CPU, i.e. Core Solo or Core Duo).

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Run in Terminal:

sysctl hw.cpu64bit_capable

If it gives 1, it means your computer has 64-bit architecture.

Or use arch command which could return either i386 (32-bit Intel) or x86_64 (64-bit Intel).

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    Running arch gives "i386". In the mean time, sysctl hw.cpu64bit_capable gives 1. Then which is it?
    – Gajus
    Jun 25, 2016 at 8:39
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Run uname -a in the shell to show details about the kernel. You can see RELEASE_X86_64 x86_64 for 64 bit version

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Open Terminal.app and run the command below:

uname -m | if grep -q 64; then echo "64-bit CPU (`uname -m`)"; else echo "32-bit CPU (`uname -m`)"; fi

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On the command line you could run ...

(
printf '\n\n'
echo 'System Software Overview:'
system_profiler SPSoftwareDataType | sed -n '/64-bit/s/[[:space:]]*\(.*\)/\1/p'
ioreg -l -p IODeviceTree | sed -n '/firmware\-abi/s/.*"\([^"]*\)".*"\([^"]*\)".*/\1: \2/p'
printf '\n\n'
echo 'Java:'
#man java_home | cat
#/usr/libexec/java_home -h  
#/usr/libexec/java_home -V
#/usr/libexec/java_home -X
/usr/libexec/java_home -d 32
/usr/libexec/java_home -d 64
printf '\n\n'
)

# sample output:
#
# System Software Overview:
# 64-bit Kernel and Extensions: No 
# firmware-abi: EFI64
#
# Java:
# /System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home
# /System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home

As already stated by Gordon Davisson, fat binaries may include both 32-bit and 64-bit executables of a program (see also Multiple Architecture, Single Build).

file /mach_kernel /usr/lib/libSystem.dylib
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    hehe, thank you for a short path! :-D I prefer just a getconf LONG_BIT from terminal, but it might be not that Jedi-way, of course
    – Farside
    Dec 27, 2016 at 16:11

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