How to Increase C Drive Space from D Drive Without Formatting in Windows

How to Increase C Drive Space from D Drive Without Formatting in Windows (10/11)

Is your C drive full and showing an alarming red bar in File Explorer? When your primary system disk runs out of storage, your PC stutters, Windows updates stop installing, and essential software crashes. On the other hand, you might have plenty of empty space sitting unused in your New Volume (D:) drive.

In this guide, you will learn how to allocate free space from D to C drive, merge D drive to C drive without format, and how to extend C drive without losing data on Windows 10 and Windows 11 completely free.

Why "Extend Volume" is Greyed Out in Disk Management:
Many users open Windows Disk Management to shrink D drive, only to discover that the Extend Volume option is disabled (greyed out) on C drive. This happens because Windows places a hidden 1 GB Recovery Partition right between C: and D:. DiskGenius bypasses this easily.

Step-by-Step: Transfer Space From D to C Drive

STEP 1

Plug In Laptop Charger & Close Background Apps

Keep your laptop connected to power and close background programs.

STEP 2

Open DiskGenius Free Edition

Download the official setup using the secure download button below and launch it as administrator.

STEP 3

Select "Extend Partition" on Local Disk (C:)

Right-click on Local Disk (C:) and click on Extend Partition (Ctrl+F12).

STEP 4

Select D Drive as Source Partition

Choose New Volume (D:) as the target partition to shrink free gigabytes from.

STEP 5

Set Transferred Capacity and Click Start

Select required GB capacity and click Start. Confirm WinPE reboot if prompted.

📥 Download Official DiskGenius Setup

Click the button below to generate your direct verified setup file.

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