When you consider Windows versions, you might immediately think of the Home or Pro editions Windows 10 Pro offers more features, but also carries a \$99 price tag to upgrade from the Home edition. Here's what you need to know to decide if professional features are worth the upgrade. Read More . While they are different, there’s another factor that separates Windows versions — whether the system is 32-bit or 64-bit.

You might have heard the terms 32-bit and 64-bit thrown around, but never really understood them. Let’s take a look at where these designations come from, and what they mean for your computing experience.

How Is the Number of Bits Determined?

Whether your computer architecture is 32-bit or 64-bit depends on the processor (also called the central processing unit, or CPU) inside your computer. Currently, the majority of computer processors fall into one of these two categories. 64-bit processors are exponentially more powerful than their 32-bit counterparts, because they can hold and process so much more information.

To understand the magnitude of the differences between the two, you have to understand a bit about counting in binary. Unlike our decimal system, which has ten digits per place, binary only has two — 0 or 1.

Thus, a 32-bit number has 2^32 possible addresses, or 4,294,967,296. Conversely, a 64-bit number’s capacity is 2^64, or 18,446,744,073,709,551,616. Comparing ~4 billion bytes (about 4 gigabytes) to ~18 quintillion bytes (about 18 billion gigabytes) showcases the difference.

Microsoft provides both 32-bit and 64-bit versions of Windows, which you can choose between when you download or install it.

How Windows Differentiates

If you’re using a 64-bit processor, you also need to use a 64-bit version of Windows to take advantage of it. 32-bit versions of Windows work on 64-bit processors, but can’t use the extra power. You can’t install a 64-bit version of Windows on 32-bit processors, but 64-bit Windows is backwards compatible with 32-bit software, as we’ll discuss.

There are two big places you’ll notice this difference in Windows. One is that a 32-bit version of Windows can only utilize up to 4 GB of RAM (or less). Thus, if you put 16 GB of RAM RAM is like short term memory. The more you multitask, the more you need. Find out how much your computer has, how to get the most out of it, or how to get more. Read More in a 32-bit installation of Windows, you’re not actually using more than 4 GB.

The other place you’ll find a difference is the Program Files folder. On a 32-bit version of Windows, apps will install to the only Program Files folder. 64-bit systems, though, have an additional Program Files (x86) folder. This is because writing software for a 32-bit architecture is vastly different from writing it for a 64-bit system.

When programs need to grab some shared information, like DLLs, to run, they need to look in the correct Program Files directory. This is why Windows keeps them separate. Note that in Windows, 32-bit is referred to as x86, and 64-bit is called x64.

Ancient versions of Windows, like Windows 3.1, ran 16-bit software. 32-bit versions of Windows are backwards-compatible with these legacy programs. If you have a 64-bit machine, however, you can’t run older 16-bit software. You’ll have to turn to emulating a 32-bit operating system.

32-bit and 64-bit Programs

Whenever you install some software, it varies by vendor whether you get a 32-bit or 64-bit version. Some developers only provide a 32-bit version, sometimes they let you choose, and still others automatically install the right version for you. If you’re running a 64-bit version of Windows, you should install the 64-bit versions of software whenever you can.

As we tested with Google Chrome Anyone who is using Windows 7, 8, or 8.1 on a computer with a 64-bit processor can use Chrome 64-bit. What's the difference? I'm glad you asked. Read More , these x64 versions probably won’t blow you away with blazing speed. However, they do take advantage of the increased security of 64-bit architecture, and could be more stable and efficient than their x86 counterparts.

Keep an eye out for links such as Versions or Editions on vendors’ download pages to see if they offer a 64-bit version. Because 32-bit software works for everyone, it’s understandably the default for most vendors. Of course, if you’re on a 32-bit system, only 32-bit software will work for you.

What Am I Running and Can I Upgrade?

Now that we’ve discussed all the details about 32 and 64-bit versions of Windows, we can find out which version you’re using Are you using a processor that supports a 64-bit operating system and are you running a 64-bit operating system? The average off-and-on PC user probably doesn't know the answers to these questions, although they should.... Read More .

There are plenty of ways to do this, but the easiest is to open the System dialogue. On Windows 8 or Windows 10, right-click the Start Button and choose System. On Windows 7 or earlier, right-click Computer and choose Properties. You can also use the Windows Key + Pause shortcut to open this menu.

Here you’ll see basic info about your computer, such as whether your version of Windows is a Home or Pro version. Under System type, Windows will tell you if your operating system and processor are 64-bit or not. You can also see your Installed RAM here. On a 32-bit system, this will note something like 4 GB usable if you have over 4 GB installed.

Your processor and operating system bit sizes should match, but if they don’t, you might be able to upgrade. If you’re running a 32-bit version of Windows 10 on a 64-bit processor, you can follow our guide to upgrade to x64 Windows Is your Windows 10 installation limited to 3.75 GB of RAM because it's the 32-bit version? We show you how to upgrade to 64-bit, so you can finally enjoy advanced features and performance. Read More . Those running a 32-bit version of Windows on a 32-bit processor can’t upgrade; you’ll need to purchase a new machine to take advantage of 64-bit.

Enough Bits

64-bit computing The packaging of a computer or computer hardware is crowded with technical terms and badges. One of the more prominent ones is 64-bit. Read More is becoming the new standard, but it’s been a rough road getting here. While there were 64-bit versions of Windows XP available, it was a headache to deal with its compatibility issues, so not many people used it. Use of 64-bit systems didn’t become too popular until Windows 7, and it’s continued up to Windows 10 today.

4 GB of RAM, which was an unfathomable amount when CPUs were first designed, is still a workable amount of memory in 2016. However, as component prices continue to drop, low-end machines will likely ship with more RAM, making 32-bit systems eventually obsolete.

This in turn will make developers focus on developing 64-bit software, which will be the standard for a long, long time. We probably won’t hit the ceiling of 2,305 petabytes of RAM It is easy to see that 500GB is more than 100GB. But how do different sizes compare? What is a gigabyte to a terabyte? Where does a petabyte fit in? Let's clear it up! Read More anytime soon!

Are you running a 32-bit or 64-bit version of Windows! Let us know what you learned in the comments!

Originally written by Karl L. Gechlik on February 23, 2010.

1. Jame Horsleys
November 4, 2017 at 1:58 pm

I use Huntron electronic test equipment. The software Huntron wrote called Workstation 3.5.4 designed for 32-bit Windows XP, will not work in Windows 64-bit S/P 2.

2. Enoch Powell
August 19, 2017 at 11:59 pm

On my older computer run several systems DOS 6.2, Windows 3.11, Windows 98SE, Windows XP and Windows XP Professional, all on different partitions.

It runs fast and smooth and the great thing is 'I am in control' Have tried Windows Vista, Windows 7, 8 and 10. These systems feel like I am in a car in reverse. So until Microsoft come up with something better will stick with what I have been using for years and am still using.

In a way it is a bit like gambling, the simpler it is the more people like it. I mean come on Microsoft, really 'Click START to STOP (Switch Off Computer).

3. Venkat
December 3, 2016 at 4:33 pm

My laptop came with Windows 8.1 and I updated to Windows 10. Due to virus i revert back to 8.1. Now, Windows 10 update is not free. How to update to Windows 10

• Ben Stegner
December 5, 2016 at 4:35 pm

This isn't really related to this article, but you're able to update back to Windows 10 without cost if you had it on your system before. Follow these steps, and Windows 10 should automatically activate:

http://www.makeuseof.com/tag/create-windows-10-installation-media/

• Venkat
December 6, 2016 at 2:46 am

Thanks!

4. Srikanth Yelkur
December 2, 2016 at 5:10 am

A nice explanation of 32 bit & 64 bit computer & OS

5. Bryan Wolfe
November 30, 2016 at 9:58 pm

Informative post. Honestly didn't know a lot of these points.

• Ben Stegner
December 5, 2016 at 4:34 pm

Glad it taught you something, Bryan!

November 30, 2016 at 5:39 pm

Shared DLLs are loaded from System and System32 folders. Not program files.

• Bruce Epper
December 4, 2016 at 7:54 pm

Many applications ship with their own DLLs which the developer may choose to put into their program directory or onto the Common Files folder under the Program Files directories. This practice is also used by Microsoft for their applications such as Office and its common components.

7. Awais Ahmed Khan
August 19, 2016 at 7:13 am

I have x64 and I didn't know that and was using 32bit OS, One day I noticed when I checked my PC RAM having 12GB Ram was showing 3Gb RAM usable well on that time I was have another PC installed with 64bit OS with x64 based processor and there was 8GB RAM without any usable problem after installing OS 64 bit problem was solved and also you can use 32 bit OS on x64 based processor but you will face RAM shoratge issue like the above article saying many things about 32 bit OS not that much worthy as x64 so also you can't intsall windows on the partition that have been crated by 32 bit OS

8. Anonymous
June 16, 2016 at 8:07 am

I have one question. my laptop computer is win7 4GB RAM and in order
to play a big data video game which operating system is better. 32 bit or
64 bit???

9. Zalifah Ibrahim
May 11, 2010 at 9:27 am

Whatever it is, the article above is clearer than any of those i have read online. Thanks Karl.

10. Anonymous
April 21, 2010 at 10:20 pm

Hi My name is Ramon i m a have question you can still run 64 bit processor amd under 32 bit operatin system? i m wondering because i installed 32 bit and i m having some trouble thanks

• Neelam Papanai
April 20, 2015 at 3:45 pm

No, you cannot Ramon....

• Bruce Epper
December 4, 2016 at 7:57 pm

Yes. A 32-bit OS works on 64-bit processors.

11. mamohitsingh
March 24, 2010 at 10:26 pm

good dvd

12. Nick
February 27, 2010 at 6:52 pm

I have supid question.
Is it any chance to install 32b XP instead of my 64b Win 7 on my laptop?

• Bruce Epper
December 4, 2016 at 7:58 pm

Yes, but you may have problems finding appropriate drivers for the hardware.

13. Oron
February 26, 2010 at 2:38 pm

Win 64 is usually SLOWER than Win 32, because every instruction and every piece of data has to be loaded in a larger chunk, and access to RAM is a bottleneck. Win 64 will be faster only when large amounts of consecutive data need to be read, such as in heavy graphics applications, video editing etc. The main advantage of 64 bit over 32 is the ability to address as much memory as you have. Which system you should use therefore depends on your intended use, and I believe many users will be better off with Wind 32.

• Jason
August 4, 2017 at 4:16 am

RAM is a bottleneck, but the hard drive is an even bigger bottleneck. 64-bit OSs can address more RAM, which is a definite win for me, since I have 8GB of RAM.

In addition, 64 bit programs can avoid more RAM accesses in the first place since they have more registers. In addition, programs aren't just double the size. Programs using the 32-bit subset of amd64 suffer no performance penalty, and even then it's only 1 byte on instructions that can already be 12 bytes or even more.

14. viraniac
February 26, 2010 at 8:53 pm

Dear Hitesh,

the 32-bit is called x86 because the first 32 bit processor is 80386, after that there is 80486,80586....

so as you can see there is 86 common with all those processors. hence 32-bit is called x86

http://en.wikipedia.org/wiki/X...

15. Ray from Las Vegas
February 24, 2010 at 8:25 am

Ok, I have a 3gb w7/32 on Laptop, and 6gb w7/64 on dual core Desktop. On Desktop, I have never used 4g of memory. Even editing videos. (I don't play games). I wish that the extra memory on x64 could be used for something.

What I see big time is that I need faster video card. Viewing HD videos takes way too much CPU.

16. Hitesh
February 24, 2010 at 6:23 am

@Karl Gechlik
I have one question?

why 32-bit called x86 rather than x32 ?

Thanks for this artical..

• viraniac
February 26, 2010 at 11:53 am

Dear Hitesh,

the 32-bit is called x86 because the first 32 bit processor is 80386, after that there is 80486,80586....

so as you can see there is 86 common with all those processors. hence 32-bit is called x86

http://en.wikipedia.org/wiki/X86

• Hitesh
February 27, 2010 at 8:20 am

Thanks viraniac,

Really What I Want To Know!

17. jollyrogue
February 24, 2010 at 1:38 am

damn.. ok, cheers Karl.

Maybe in the future i'll purchase a 64bit version.

18. Karl Gechlik
February 23, 2010 at 9:46 am

A 32 Bit OS CAN USE 4GB of memory that 4GB of memory can then be distributed to an on board graphic card that needs memory but if you are using an addon graphics card with its own memory than you can very well use and see 4gb of ram in Windows 32bit.

• Aeiluindae
February 23, 2010 at 12:37 pm

Just to note, 4 GB of memory looks a awful lot like 3.7 GB, depending on how the OS is reporting it. For example, my Windows 7 system with 4 GB of RAM reports 4 GB, 3.75 usable on 64-bit windows, because of my integrated graphics, most likely.
Similarly (and this is why hard drives actual sizes are always smaller than the number on the box, a couple different reporting schemes (base 10 and base 2) are used. Base 10, as I understand it, uses a megabyte made of 1000 kilobytes, and thus reports more MB of space, where base 2, with a 1024 kilobyte megabyte, reports less MB. The box uses base 10, the computer uses base 2.

• Karl Gechlik
February 23, 2010 at 12:43 pm

And i didn't state that because it is confusing. But you are correct.

• Doc
February 23, 2010 at 7:54 pm

@Karl Gechlik: No, no computer with a 32-bit OS can see the full 4GB. See the image at http://www.codinghorror.com/blog/2007/03/dude-wheres-my-4-gigabytes-of-ram.html

in order to see why (with only 4GB, take away the top gray bar): Your video card GART remapping (which is required for your CPU to write to video card RAM, whether your video card is in a slot OR onboard), DMA buffers, your motherboard BIOS, registers for controlling your other devices (USB, sound card, hard drive controllers, keyboard, mouse...almost anything you can see in Device Manager)...all of it detracts from the full 4GB of RAM you may have installed. Your memory is still there; it's just that in order to function, your devices need memory addresses to talk to the OS, so they "cover" chunks of RAM with their own registers or memory.

• B.G.
February 24, 2010 at 3:41 am

Doc, your statement is incorrect. Your statement is solely based on the fact that Microsoft limit physical addressing to 4GB on 32-bit OS's since after XP SP1. It is possible for 32-bit systems to use as much RAM as 64-bit systems.

Mr Gechlik, your calculation of 2^64 is incorrect as bit 63 is used as the NX bit, so halve what you have calculated.

• Bruce Epper
December 4, 2016 at 8:18 pm

Add-in video cards are going to grab a chunk of system RAM below the 4GB mark, too. It isn't all of the memory being used for video as is the case for integrated graphics, but it will grab some (128 MB for my GTX 560) to provide a window of directly addressable memory for CPU interaction.

• Jason
August 4, 2017 at 4:17 am

Not true; even with dedicated graphics on my Inspiron 530 a 32 bit OS shows less than 4GB of usable RAM. A 64-bit OS showed all 4GB, and ran more stably too (the 32-bit OS was running out of address space.)

19. Doc
February 23, 2010 at 9:25 am

@Greymarch: Most 32-bit machines will have 3.5 or 3.75GB of usable address space, not 3.0 (depending on the video card's graphics aperture (GART), which allows the OS to directly write to video memory). Having a 64-bit OS (on a 64-bit CPU) allows that memory to be "moved" above the 4GB mark, making it available again. Also, some Windows server OS's allow more than 4GB of RAM in a 32-bit OS (but, notably, NO desktop OS's) via Physical Address Extension (PAE), which Microsoft mysteriously doesn't enable under 32-bit (but can).

I've also seen many machines ship with 64-bit Windows Vista, and know of one recent system that has Windows XP 64-bit Edition (which is built on the core of Server 2003).

You are also constrained to the memory your motherboard and OS can support - the system I'm typing on can only support 4GB, the XP 64 system can handle 8GB, and my Phenom quad-core can handle 16GB. The memory limits for Windows 7 are
Home Basic: 8GB
Starter: 2GB

20. Ben
February 23, 2010 at 9:19 am

A 32-bit program will work the same whether it's installed on a 64-bit system or a 32-bit system.

• Karl Gechlik
February 23, 2010 at 9:47 am

That is correct.

21. jollyr
February 23, 2010 at 8:35 am

Using the student offer here in the UK i was able to get hold of the 32bit Win7 Pro.

Anyone know if it's possible to use the license key from that with a downloaded 64bit version? I'd like to buy more RAM for my laptop.

• Karl Gechlik
February 23, 2010 at 9:47 am

That will not work you will need to purchase a 64bit license.

• jollyr
February 23, 2010 at 4:38 pm

damn.. ok, cheers Karl.

Maybe in the future i'll purchase a 64bit version.

• Bruce Epper
December 4, 2016 at 8:22 pm

Are you sure? My Win 7 key works on both the 32-bit and 64-bit versions.

• Ron MVP
December 6, 2016 at 1:52 am

You are mistaken Karl.

Windows (and Office) Product Keys allow you to install and activate either 32 or 64 bit as you decide.

22. Jon
February 23, 2010 at 8:35 am

Dedo is correct, although he has it slightly off. 32-bit OS can allocate 4 GB of physical memory, but it mirrors some of that memory with the memory some devices (like graphics cards) contain. Therefore, if you have 4GB RAM installed, and a 256MB VRAM video card, WinXP (32-bit) will mirror the 256MB of VRAM in it's own RAM, and only allow 3.75GB of physical RAM to be allocated by the rest of the system. There are other devices on board that also contain their own memory, which the OS also mirrors, but graphics cards are the greatest impact.

23. Dedo
February 23, 2010 at 8:10 am

I was under the impression that 32bit can address 4gb of ram TOTAL, which includes video card and any other physical ram. if you have two 512 video cards in SLI, 32bit windows will only see 2.75gb ram. if you have one 256mb graphics card, windows will see 3.5gb

maybe i'm mistaken

24. Greymarch
February 23, 2010 at 7:51 am

The article has a mistake. The article should really mention that 32-bit versions of Windows can only address 3 gigabytes of memory, not 4 gigabytes. Considering that most computer systems jump from 2 gigabytes to 4 gigabytes, that is an important distinction. A user who has 4 gigabytes, after reading this article, may think that they are using all 4 gigabytes with a Win32 OS, but they would be wrong. Please clarify this.

- Greymarch
I write about technology at my website
http://www.greymarch.com

• Sats
April 24, 2010 at 9:56 am

I toataly agree to greymarch.. RAM size should be 3 GB

• Bruce Epper
December 4, 2016 at 8:24 pm

Four is correct, not 3.

• Jason
August 4, 2017 at 4:20 am

No, it's only 3. Programs under Windows could originally only access 2GB of RAM in user mode. Programs started using nasty tricks like comparing the upper bit of the address to check if it was a kernel or user address (negative numbers in x86 have '1' as their upper bit). When Microsoft allowed 3GB to be available to user mode programs, they had to indicate they were compatible with a special flag. However, 1GB is still reserved for the kernel, and even in 64-bit Windows, the upper half of the address space is reserved for the kernel. (However, the address space is a lot larger, so it isn't an issue yet.)

25. Dan Hutten
February 23, 2010 at 5:38 pm

good to know, thanks jon

26. jollyrogue
February 23, 2010 at 5:35 pm

Using the student offer here in the UK i was able to get hold of the 32bit Win7 Pro.

Anyone know if it's possible to use the license key from that with a downloaded 64bit version? I'd like to buy more RAM for my laptop.

27. Dan Hutten
February 23, 2010 at 5:10 pm

I was under the impression that 32bit can address 4gb of ram TOTAL, which includes video card and any other physical ram. if you have two 512 video cards in SLI, 32bit windows will only see 2.75gb ram. if you have one 256mb graphics card, windows will see 3.5gb

maybe i'm mistaken

28. Greymarch
February 23, 2010 at 4:51 pm

The article has a mistake. The article should really mention that 32-bit versions of Windows can only address 3 gigabytes of memory, not 4 gigabytes. Considering that most computer systems jump from 2 gigabytes to 4 gigabytes, that is an important distinction. A user who has 4 gigabytes, after reading this article, may think that they are using all 4 gigabytes with a Win32 OS, but they would be wrong. Please clarify this.

- Greymarch
I write about technology at my website
http://www.greymarch.com

• crisse
January 5, 2015 at 9:02 pm

check this to change your 32 bit version of windows to make it recognize all ram you have .

http://www.unawave.de/windows-7-tipps/32-bit-ram-barrier.html?lang=EN

just apply a patch.

I tested it .

from 3,25 GB recognized now it is a full four.

so yes the patch works.

• Mihir Patkar
January 7, 2015 at 9:31 am

Nice one, crisse!