Possible reasons for Extend Volume Grayed out are shown here, and users will be given corresponding solutions at the same time.

1. Why Extend Volume Grayed out and How to
Solve it
When system prompts a certain partition is running out of space or there is no enough
space to save new files, we believe every user would want to extend the very partition as
soon as possible. Therefore, since Windows Vista, Microsoft adds the feature "Extend
Volume" to system built-in Disk Management program. But disappointingly, the
problem Extend Volume Grayed out often appears, like the following image shows:
--Source from
http://www.partitionwizard.com/resizepartition/extend-volume-grayed-out.html
What’s the reason? In this article, we will show users 2 possible factors as well as give
corresponding solutions. Note: this article is all about basic disk rather than dynamic disk.
Reasons for Extend Volume Grayed out

2. In one of the following 3 situations, "Extend Volume" will not work:
1.The partition users want to extend is not a NTFS partition. Microsoft says extending
volume feature in Disk Management only works to a raw or NTFS partition.
2.There is no unallocated or free space on hard disk or the space is not contiguous and
after the partition which needs extending.
3.Users want to extend a primary partition, but there is just a free space right after the
target partition.
Now that Windows "Extend Volume" will be grayed out under these situations, users
would want to get some wonderful solutions. Currently, there is partitioning tool which can
extend a partition without limitations, and MiniTool Partition Wizard can be chosen.
Extend Partition with MiniTool Partition Wizard
MiniTool Partition Wizard can help users extend both FAT partition and NTFS partition no
matter whether there is unallocated space on hard disk. Next, let’s take extending a
FAT32 partition in Windows 7 for example.
Firstly, launch the partitioning tool to open its main interface:

3. Then, select the partition which needs extending (here, we extend partition G which is a
FAT32 partition, and there is no unallocated space contiguous the partition), and then click
the function "Extend Partition" from action panel.

4. Next, expand partition G by taking free space from an existing partition or from an
unallocated space and drag sliding button to decide how much space to take.

5. At last, apply all changes if they are satisfying.
After application, the selected FAT32 partition will be extended. Now, download the
partitioning tool MiniTool Partition Wizard to solve the problem Extend Volume Gray out.