If you want to see how fast your network really is, or test the speed between two hard drives, then you need files to do it. Today we’ll tell you how to create “dummy” files so you can perform such tests.

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Say you’ve installed a fast new solid state drive in your computer, and want to see how fast they really are. Or maybe you’ve finally upgrade your entire setup to gigabit ethernet or wireless AC, and you want to know how well it performs. Maybe you even want to compare the two.

The “theoretical” speeds on the box won’t really tell you how something performs in your home–you’ll need to test those transfer speeds yourself. To do so, you’ll need a file or files of the same size. Luckily, you can create dummy files of any size in Windows to serve this purpose–no extra software required.

How to Create Dummy Files on Windows

All you need is to open a command line and type a few quick commands. It works in any version of Windows, too. Press the “Windows + R” key combination to open the Run window and then type “cmd”. Press OK.

With a command prompt open, you can start creating dummy files to your heart’s content. To do this, we’re going to use Fsutil.exe, which is a built-in file system tool that allows you to perform file system operations from the command line.

Here is the syntax we want to use for creating dummy files:

fsutil file createnew filename length

The length of the file needs to be in bytes, so if you’re unsure how to convert a large file into bytes, then here are the values you need to enter to actually obtain the sizes you might want:

1 MB = 1048576 bytes

100 MB = 104857600 bytes

1 GB = 1073741824 bytes

10 GB = 10737418240 bytes

100 GB = 107374182400 bytes

1 TB = 1099511627776 bytes

So, this is what we’ll use in our syntax for creating a 1 gigabyte dummy file:

fsutil file createnew fakefile.txt 1073741824

Just enter or copy-paste that text into your command line and hit “Enter” and your dummy file will be generated.

Once we create our new dummy file, (entering the true byte value of 1 gigabyte), we can right-click and select “Properties” to see its size, which is exactly 1 GB.

Of course, you might not be able to remember the exact byte size of one gigabtye or a terabtyte, but if you really need to, you can just refer to this article!

Now you can easily create dummy files of any size on your Windows PC–no more searching your computer for files of approximate sizes. With just a few key presses, you’ll be able to create exactly what you want and get the answers you need.

Testing Things Out

Once you’ve created a dummy file, you can use it to test out transfer speeds for anything ranging from a simple USB flash drive to your fancy new home network.

Testing transfer speeds with a dummy file is about as easy as you can imagine. For example, let’s say we want to test how long it takes to write a 10 gigabyte file to a flash drive over USB 2 versus USB 3. To do this, all we really need is a flash drive , a computer with both types of USB ports, and a stopwatch.

We’re going to use a 10GB file because we’re more likely to see a difference in transfer times with a larger file than with a smaller one. With smaller files, the difference will be significantly less noticeable.

First plug the flash drive into a USB 2 port (they are black, while USB 3 ports are blue), then drop the file onto the drive and start the stopwatch as you do.

As you can see from the following screenshots, the difference to copy a 10 GB file to a flash drive over a USB 2 connection versus a USB 3 connection is quite significant. On the left is the USB 2 time, and on the right is the USB 3. The USB 3 transfer is over two full minutes faster than USB 2.

You can repeat this test for any kind of transfers you desire. Feel free to test how long it takes to move a file from one computer on your network to another, to a cloud drive, or compare speeds between devices, such as how long it takes to transfer a file to one drive versus another.

There’s no limit to what you can test and time so if you’ve been wondering about the performance of your various devices, Internet connection, or network transfers, then create a dummy file and wonder no more.

Profile Photo for Matt Klein Matt Klein
Matt Klein has nearly two decades of technical writing experience. He's covered Windows, Android, macOS, Microsoft Office, and everything in between. He's even written a book, The How-To Geek Guide to Windows 8.
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