Why my external hard drive has less space than it should?

It's understandable to be surprised when a new external hard drive has less space than it should. Here are some common reasons why this happens, along with explanations:

When you format a drive, some space is used for file system structures (like the file allocation table, root directory, etc.), which reduces the available space slightly. However, for a 1TB drive, this difference is usually only a few gigabytes. NTFS is efficient, but some space is always reserved for system files and metadata.
Some drives come with pre-installed software, backup tools, or hidden recovery partitions that occupy space. You mentioned no visible partitions, but it's worth double-checking: 
Use Disk Management (diskmgmt.msc) to see if there are any hidden or unrecognized partitions.
If there are recovery partitions, they may take up a small amount of space.
Rarely, if the drive has manufacturing defects, some space might be marked as bad sectors or reserved, but this is uncommon with new drives.
The most likely reason for the "less than expected" space is the difference between decimal (manufacturer's) and binary (Windows) measurements, which accounts for about 7-8% difference. For example, a 1TB drive (decimal) will typically show as around 930 GB in Windows.

What You Can do if external hard drive has less space than it should:
* Use a disk utility tool like Crysta1DiskInfo or Diskp0rt to see the total capacity and check for any hidden or reserved partitions.
* Open Disk Management and review all partitions on the drive.
* If the drive shows around 930 GB in disk management, it’s normal and nothing to worry about.