External hard drive unallocated space appears in different
situations
The external hard drive with 2 terabytes could count as the dividing line for those
situations that will be discussed in this part. One is the external hard drive with
a size less than 2 TB has unallocated space. It also might has partitions like G
drive, H drive, and then has unallocated space on external hard drive. In this
condition, you can either add the unallocated room to partition or create new partition with that space.
The other is external hard drive with the size more than 2 TB, say 3 TB drive, has
unallocated space. This space could be treated as above drive if the partition table
is GPT instead of MBR type because MBR disk supports the capability up to 2 TB while
GPT style doesn’t have this limitation. If not, you need convert MBR disk to GPT disk to
make use of the unallocated space.
The last situation that external hard drive has unallocated space would be new bought
hard drive. Every drive should be formatted and partitioned before you use it.
Therefore, you can try quick partition the new external hard drive.
How to use unallocated space on external hard drive?
For external hard drive whether overpass 2 TB or not with used partitions and
unallocated space, the solutions aim to them have little difference after partition
table converting. Therefore, two specific solutions will be illustrated in next
part, one is for add unallocated space to partition, the other is for quick
partition new drive.
Add unallocated space to partition on external hard drive
Check out the location of the unallocated room in the Disk Management. If the
unallocated space is adjacent to the target partition from the right side, you can
use Disk Management to finish this job directly. Right-click the designed partition,
select Extend Volume. Then drag the arrow to cover the unallocated
space, and then click OK. If the unallocated space is separated by
other partitions on the disk, you need to turn to third party software now. AOMEI Partition Assistant Standardis free partition manger for Windows XP/Vista/7/8/10. It can solve this issue withMerge Partitions feature. Download it to have a try.
Step1. Install and launch Partition Assistant. Right-click the
unallocated space, and select Merge Partitions.

Step2. Check the unallocated space as well as the target partition.
You can select any partition of them as the target partition.

Step3. Now you got 255 GB in D drive. Click Applyto
execute the pending operation.

Quick partition new external hard drive
In order to reach this goal, you also got two ways, Disk Management and AOMEI
Partition Assistant Standard. In Disk Management, right click the new drive, and
select New Simple Volume. Then pop-up window of creating new simple
volume will come into your sight. The rest you need to do is follow the wizard, in
which you will decide the partition size, assign the drive letter and choose the
file system. This process will format this external hard automatically. If you want
to create more than two partitions in this hard drive, then you need to repeat above
steps. Or, you can try another easy and fast path. Do quick partition using AOMEI Partition
Assistant Pro.
Step1. Install AOMEI Partition Assistant Pro. Right click the new
drive and select Quick Partition.

Step2. Configure specific partition settings (partition numbers,
disk type, partition size, and partition labels) in this window. Click Start
Partitioning after your configuration.

Step3. Wait the process to be finished for a few minutes, and then
you will see the outcome.

Conclusion
No matter in what situation you have external hard drive unallocated space, AOMEI
Partition Assistant could help you make use of it. With this freeware, you can reformat to FAT32 from NTFS
file system. You even can do above operations on the internal hard disk in which the
OS is on. This software has many helpful features, such as migrate OS to SSD, copy
disk/partition, Windows To Go creator and so on. By the way, this freeware supports
only Windows PC operating systems. If you’re running Windows Server like Server
2003/2008/2011/2012/2016 etc, you might as well turn to AOMEI Partition Assistant
Server which specially designed for Server users.