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Josef Biehler
Josef Biehler

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Know the bitness of your .NET application

32Bit or 64Bit - Can you tell?

While developing a .NET profiler, I struggled a bit with the bitness of my test application. So I decided to write down my findings. If you want to read more about the profiler, you should follow my series about it:


Do you know this Any Cpu, that is selected per default in Visual Studio:

I see this all day long but never asked myself what this actually means. So I went to stackoverflow and found a very good answer. When compiled with Any CPU the app will be executed as 32Bit or 64Bit process. This table shows how an app will be executed:

X86 Windows x64 Windows
Any CPU 32 Bit app 64 Bit app
Any CPU (prefer 32Bit) 32 Bit app WoW64 App (simulation of 32Bit applications under Windows 64Bit)

So using Any CPU you need not to publish your app in two versions.

Prefer 32 Bit

But what means Prefer 32 Bit? Right-click onto your project and go to Properties > Build. Here you should see a checkbox:

Explicitly set the bitness

Above the checkbox you can set the bitness of your app explicitly in the target platform dropdown:

Proving the bitness

OK. You compiled your app with Any CPU and you execute it somewhere. How can you determine the bitness? This is easy. Open the task manager, find your process and read the content of the platform column:

Installation paths

You want to see the installed versions of .NET framework? On my Windows 10, the runtimes are installed in this path: C:\Windows\Microsoft.NET.

Checking the bitness in your code

An old trick is to request the size of IntPtr which will be 4 bytes within a 32Bit process and 8 bytes within a 64Bit process:

Console.WriteLine($"IntPtr size: {IntPtr.Size}");

Since .NET4 you can use:

Console.WriteLine($"System.Environment.Is64BitOperatingSystem: {System.Environment.Is64BitOperatingSystem}");
Console.WriteLine($"System.Environment.Is64BitProcess: {System.Environment.Is64BitProcess}");

On my Windows I get this result:


I think in most cases you don't need to care attention about the bitness. But if you have to, this article hopefully helps you a bit.

Found a typo?

As I am not a native English speaker, it is very likely that you will find an error. In this case, feel free to create a pull request here: . Also please open a PR for all other kind of errors.

Do not worry about merge conflicts. I will resolve them on my own.

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