Most PC users allocate less than 25GB space to the system partition while installing Windows operating system. While 25GB of free space is good enough for users who don’t install apps that require huge disk space, it’s always a good idea to allocate at least 50GB of space to the system drive. If your Windows drive (system drive) is running out of free disk space, you can add more space to the existing partition without having to reinstall the operating system, provided that you have free, unused space on the hard drive. Even though extending a system partition isn’t as difficult as it sounds and can be done with or without the help of third-party tools, it’s advisable to backup all data before beginning to follow our instructions. Extending your system drive (“C” drive) Follow one of the two methods given below to extend system drive in Windows 1o or Windows 8.1. IMPORTANT: We recommend you backup all data before beginning to extend the system partition and we are not responsible for any data loss that may occur during the process. We recommend you create a system image backup to an external drive before proceeding further. Method 1 Extending system partition using Windows Disk Management Tool While it’s possible to extend the system partition using Windows Disk Management tool, there must be some unallocated space right next to the system partition. If you don’t have some unallocated space next to the system drive, Windows will not show extend volume option even if you have enough free space on another partition. If you don’t have the required amount of unallocated space next to system partition in the partition table, follow the easy instructions provided in Method 2 to successfully extend your system drive. Step 1: Open Run dialog box by simultaneously pressing Windows and R keys. Type Diskmgmt.msc in the box and then press Enter key to open Disk Management. Alternatively, you can right-click on the Start button and click Disk Management option to quickly launch it. Go through our how to open Disk Management in Windows 10/8.1 guide to know all four ways to open Disk Management tool. Step 2: Once Disk Management is launched, check if you have unallocated space next to the system drive. If you don’t have unallocated space, follow the steps in Method 2. If there is required amount of unallocated space, right-click on your system drive and click Extend Volume option to launch Extend Volume Wizard. Step 3: Click Next button to see the maximum disk space that can be added to your system partition. Type the amount disk space you would like to add to the system drive in the box next to Select the amount of space in MB, and then click Next button to extend the partition. That’s it! Method 2 Extending system partition using MiniTool Partition Wizard Home Edition (free) As you probably know, Partition Wizard is the best free software out there to manage hard drives in Windows operating system. Even though it’s not as popular as some other similar tools, it’s definitely better than all other free partitioning tools out there. The main advantage of this tool over Windows Disk Management is that Partition Wizard lets you extend your system partition even if you don’t have unallocated space on the right of your system partition in the partition table. It lets you extend the system partition by taking required free space from a partition that has enough disk space. Step 1: Download Partition Wizard Home edition software. It’s completely free and supports both 32-bit and 64-bit systems. Run the setup file and then follow the simple on-screen instructions to install it on your PC. Step 2: Close all other programs and launch Partition Wizard software. On the welcome screen, click MiniTool Partition Wizard tile to launch the same. Step 3: Right-click on the system drive and then click Extend option to open Extend Partition dialog. Step 4: Here, select a partition from where you would like to take the free space from (the partition must have free space!), specify the amount of disk space that you would like to add to your system drive by moving the slider, and then click OK button. Step 5: Finally, click Apply button and click Yes button when you see the confirmation dialog box to begin extending the system partition. Note that Partition Wizard might ask you restart the PC to extend the system partition. When asked, restart your PC to complete the job. Hope this helps!