Did you know that Windows includes a utility that allows you to quickly generate a file of any size instantly.

It is called fsutil, there are many tasks that are related to file allocation table (FAT) and NTFS file systems, such as managing reparse points, managing sparse files, or dismounting a volume. If it’s used without parameters, fsutil displays a list of supported subcommands.

You must be logged on as an administrator or a member of the Administrators group to use fsutil. This command is quite powerful and should be used only by advanced users who have a thorough knowledge of Windows operating systems.

You must enable Windows Subsystem for Linux before you can run fsutil. Run the following command as Administrator in PowerShell to enable this optional feature:

Open an administrative level command prompt.

Enable-WindowsOptionalFeature -Online -FeatureName Microsoft-Windows-Subsystem-Linux

You’ll be prompted to restart your computer once it’s installed. After your computer restarts, you’ll be able to run Fsutil as an administrator.


Here is the syntax of the command to create a file

fsutil file createnew <file> <size in bytes>

Parameter Description
createnew Creates a file of the specified name and size, with content that consists of zeroes.
<length> Specifies the file’s valid data length.

For example, this command will create a 1GB file called 1gb.test on my desktop:

This command will create a 1mB file called testfile1mb.txt in my test folder

> fsutil file createnew J:\windows\test\testfile1mb.txt 1048576

This one will create a 100mB file called testfile100mb.txt in my test folder

> fsutil file createnew J:\windows\test\testfile100mb.txt 104857600

This is what i saw in my test folder

The key is to input the size of the file in bytes, so here are some common file sizes to save you from math:

1 MB = 1048576 bytes
100 MB = 104857600 bytes
1 GB = 1073741824 bytes
10 GB = 10737418240 bytes
100 GB =107374182400 bytes
1 TB = 1099511627776 bytes
10 TB =10995116277760 bytes