These are the fastest options. You simply type in your desired GB, and they give you the exact MB or MiB value to enter into Windows Disk Management.
If you want a tool that calculates and performs the partition for you, several reputable brands offer free versions:
: Many users prefer "round" numbers for their drive sizes for better organization and visual clarity in their file manager. Super User Top Free Partition Calculators & Tools (2026)
While operating systems like Windows or macOS have built-in disk management tools, they often rely on a confusing unit system. Should you use MB or MiB? What is the exact number to type into the box to get a "clean" 100GB partition without losing space to rounding errors?