32 or 64 bits, what's the difference?

Usually, the one who chooses the higher number is right, but the matter is not as simple as it seems. If 64-bit computers have been on the market for more than twenty years, why does the choice still exist? The answer is a mixture of technical limitations, historical decisions, and habit.

What does "being" actually mean?

A bit is the smallest unit of data, a zero or a one. When we say that a processor, operating system, or program is 32- or 64-bit, we are primarily referring to the width of the basic data units it uses to calculate and the length of the memory addresses it uses to find its data. So the designation does not automatically indicate that the program is better, but rather what environment it was built for.

Addresses can be thought of as house numbers on a memory street. With 32 bits, just over 4.2 billion can be written, which is equivalent to 4 gigabytes of memory. With 64 bits, the theoretical limit is 16 exabytes, more than four billion times more. Actual processors do not fully utilize this space, but the limits are still far beyond anything a home computer can handle.

Four gigabyte ceiling

This limit is most tangible in everyday life. When computers had a few tens of megabytes of memory, the ceiling was practically invisible. Today, however, even a browser (we all know that we mean Chrome) with many tabs can consume several gigabytes.

If you install 4 GB or more of RAM on a 32-bit Windows, the system will often only display about 3 to 3.5 GB of usable memory, because some of the address space is reserved by devices, such as the graphics card. In addition, in 32-bit Windows, each 32-bit process has only 2 GB of virtual address space available by default. Although the PAE extension allows 32-bit systems to address more physical memory in principle, Microsoft still lists an upper limit of 4 GB for 32-bit Windows 10.

For 64-bit versions of Windows 11, the limitations are primarily determined by the edition of the system. Home supports up to 128 GB, Pro up to 2 TB, and Pro for Workstations and Enterprise up to 6 TB.

How the 64-bit world came to desktops

The transition was not a given. Intel and Hewlett-Packard (HP) designed a completely new IA-64 architecture, known for its Itanium processors, which was incompatible with 32-bit x86. AMD was not invited to develop it, so it took a different path. It extended the existing x86 architecture with 64-bit capabilities and kept running legacy programs. AMD64 was announced in 1999, and the full specification was released in August 2000.

The first processor with the new instruction set, the Opteron, was released in April 2003, followed by the Athlon 64, the first 64-bit processor aimed at the average user, on September 23 of the same year. Intel then introduced a compatible solution called Intel 64, and Microsoft released Windows XP Professional x64 Edition on April 25, 2005. The often cited year 2001 refers to a second version aimed at Itanium processors, which soon disappeared from the market.

Who can start what?

The rule is simple, but asymmetrical. A 32-bit program works on both a 32-bit and a 64-bit operating system, while a 64-bit program requires a 64-bit system on a 64-bit processor. In Windows, this is made possible by the WOW64 layer, so a 64-bit system contains a Program Files (x86) folder in addition to the Program Files folder, where 32-bit programs are installed.

Compatibility also has limits. 64-bit Windows requires 64-bit drivers, so an older printer or scanner without the appropriate driver may no longer work, and 16-bit programs may not run at all.

Is 64-bit always faster?

Not necessarily. A 64-bit program can use more memory, and on x86-64 processors it also has 16 general-purpose registers instead of 8, which allows compilers to write more efficient code. The larger address space also allows for more efficient security mechanisms, such as random memory allocation. On the other hand, pointers are twice as long, so 64-bit programs tend to use slightly more memory.

For simple tasks like writing text or viewing PDFs, you'll barely notice the difference. It becomes noticeable when editing video, using large spreadsheets, running virtual machines, and playing demanding games. But there's something else that's important. A 64-bit program simply won't run on a 32-bit system.

Phones and tablets went away earlier

On mobile devices, the transition was faster, as manufacturers control the hardware, system, and app store. Apple has required 64-bit versions of new apps since June 2015, so its 2017 operating system iOS 11 no longer ran 32-bit apps. Devices with 32-bit processors, such as the iPhone 5 and 5c, could not be upgraded to it at all. On Macs, macOS Catalina in 2019 was the first release without support for 32-bit programs.

Android has supported 64-bit processors since version 5.0 Lollipop. The Google Play Store has also required 64-bit versions of new apps with native code since August 1, 2019, and has stopped offering apps without them on 64-bit devices since August 2021. Arm announced in 2020 that its large processor cores would be 64-bit only from 2022.

Why 32-bit versions don't disappear overnight

Reasons to 32-bit versions don't disappear overnight, there are more. First, there are older computers that have a 32-bit system or processor. Then there are add-ons and plugins. If a 32-bit add-on only works with the 32-bit version of the program, the user has no choice. The third reason is industrial and embedded equipment, as Arm maintains 32-bit support in the Cortex-M and Cortex-R families that power microcontrollers. The fourth reason is cost. Transforming legacy code requires time and money, which maintainers don't always have.

The pressure is mounting. Windows 11 only exists as a 64-bit system, and Microsoft ended regular support for Windows 10, which offered both versions, a year ago, on October 14, 2025. Valve announced the end of support for 32-bit Windows in the Steam client on January 1, 2026. According to a survey in August 2025, only 0.01 percent of such systems existed, and 32-bit games continue to run on 64-bit Windows.

How to check if you have 32-bit or 64-bit Windows?

In Windows, open Settings, then System, and then About. The System type line will tell you whether you have a 64-bit operating system and an x64 processor. If your system is 32-bit and your processor is x64, your computer is doing more than the system allows, and is unnecessarily consuming memory. In Task Manager, you may notice 32 bit next to 32-bit programs on the Processes tab.

Simple rule

If your system and processor support 64-bit, choose the 64-bit version. Choose 32-bit only when required by the system, add-on, driver, or hardware. If you're still running 32-bit Windows on a computer that could otherwise handle more, upgrading usually makes sense, not for speed, but for memory, security, and support for modern programs.

Once upon a time, the numbers 32 and 64 were the dividing line between two worlds. Today, they are more of a sign of a transition that is almost complete, but with each installation, they still gently remind us of how long it takes to say goodbye to the old.