How to Increase C Drive Space on Windows 10 (2026 Guide)

Is your C drive almost full? The C drive holds Windows system files, installed programs, updates, and the page file, so it fills up faster than any other partition. When the primary drive runs out of space, Windows slows down, updates fail, and apps start misbehaving. The good news is that you can free up space or physically expand the drive without reinstalling Windows. This guide shows you how to increase C drive space on Windows 10 in 2026.

Why the C Drive Fills Up So Fast

Windows reserves a lot of room for itself. System restore points, Windows Update cache, temporary files, hibernation files, and the virtual memory page file can quietly eat tens of gigabytes. Installed programs and games also default to the C drive unless you change the installation path. Over time, hidden folders such as WindowsApps grow without you noticing. If you want to see what is really taking up space, check out our guide on accessing the WindowsApps folder to spot the biggest culprits.

Quick Wins: Free Space Without Resizing

Before you touch any partitions, try the simplest cleanup steps first. These methods are safe, take minutes, and often recover 10 to 30 GB on an old system.

• Open Settings > System > Storage and turn on Storage Sense to delete temporary files automatically.
• Run Disk Cleanup (type cleanmgr in the Start menu) and click Clean up system files to remove old Windows updates.
• Empty the Recycle Bin and delete the Temp folders in %temp%, C:\Windows\Temp, and C:\Windows\SoftwareDistribution\Download.
• Uninstall programs you no longer use from Settings > Apps.
• Move personal files such as Downloads, Documents, and Videos to another partition.

If cleanup is not enough, you can expand the C drive itself using the native Windows tools described below.

Method 1: Extend the C Drive with Disk Management

Disk Management can extend the C drive, but only into unallocated space that sits directly next to it. If your D drive is adjacent, you need to delete or shrink it first, so back up anything important before you begin. Shrinking a volume is safe, but deleting one is not.

1. Right-click the Start button and select Disk Management.
2. Right-click the D partition and choose Delete Volume (after backing it up) to turn it into unallocated space.
3. Right-click the C partition and select Extend Volume.
4. Follow the wizard, set the amount of space to add, and click Finish.

The Extend Volume option only works on NTFS partitions. FAT32 and exFAT drives do not support extending this way, and you cannot extend C into space that is not directly adjacent to it.

Method 2: Extend the C Drive with Diskpart

Diskpart is a command-line tool that can do the same job when Disk Management is greyed out. It also requires unallocated space next to the C drive, and the target partition must be NTFS.

1. Right-click the Start menu and open Windows PowerShell (Admin) or Command Prompt (Admin).
2. Type diskpart and press Enter.
3. Type list volume and note the volume number of your C drive.
4. Type select volume *, replacing * with the C drive volume number.
5. Type extend size=XXXX, replacing XXXX with the size in MB you want to add, then press Enter.

If Diskpart reports that there is not enough usable space, the free space is not adjacent to C. You will need third-party partition software or a full backup and repartition to rearrange the layout.

Move Heavy Files and Folders to Another Drive

You do not have to resize anything to keep the C drive healthy. Moving large libraries and app data to D or E gives you breathing room without touching partitions. Right-click Downloads, Documents, or Videos in File Explorer, open Properties > Location, and set a new path on another drive.

You can also move the page file and the print spooler folder to a secondary drive through System Properties. If you record gameplay, point your recordings elsewhere too: our guide on where OBS saves recordings shows how to change the recording path so your captures never fill up the C drive.

Clean Up Windows.old and Update Cache

After a major Windows feature update, an old system folder called Windows.old can linger and consume 20 GB or more. Use Disk Cleanup and select Previous Windows installation(s) to remove it safely. Remember that deleting it means you cannot roll back to the previous version, so only do this once you are sure everything works.

Keeping the system drive tidy also prevents other hardware headaches, so it is worth checking the rest of your PC for common issues every few months.

Frequently Asked Questions

Can I increase C drive space without deleting D drive?

Yes, if there is already unallocated space next to C. If not, you can shrink D in Disk Management to create unallocated space, as long as the space ends up directly adjacent to C.

Is it safe to extend the C drive?

Extending into unallocated space does not delete data, but shrinking or deleting adjacent partitions does. Always back up important files before changing partitions.

Why is the Extend Volume option greyed out?

The option is greyed out when there is no adjacent unallocated space, or when the C drive is not NTFS. Move or create unallocated space next to C, then try again.

Final Thoughts

Increasing C drive space on Windows 10 comes down to two things: cleaning up what you no longer need, and expanding the partition with Disk Management or Diskpart. Start with the quick cleanup steps and only resize the drive if you still need more room. Keep your primary drive at least 15 to 20 percent free and Windows will stay fast and reliable.

For more Windows tips, check out our list of must-have apps for Windows 11 and our guide on downgrading from Windows 11 to Windows 10 if you are thinking about switching.