Why 1 TB HDD shows 931 GB only. Reason & Solution.

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If you’ve ever purchased a computer with a hard disk capacity of 1 TB or any other external HDD and opened it. You may have find it that its only 931 GB & you may be wondering where all those other 69 GB went. why hdd is showing up less space than mentioned ? Means why 1 TB HDD shows 931 GB only.

There are several reasons Windows could display the wrong amount of available space that might be due to invisible shadow files, formatting overhead and hidden recovery partitions.

Have you ever thought why Hard Drive Shows Less Space than Advertised GB ?

You may have noticed that they always have less space than mentioned once they’re formatted. The reason for this difference is due to the way hard drive manufacturers advertise it versus the way Windows computers actually use the storage devices.

To a Hard Disk Drive (HDD) Manufacturer Company,

Example for 1 TB Hard Disk. From a HDD Manufacturer side 1 KB means 1000 bytes, 1 MB means 1000 KB, 1 GB means 1000 MB & 1 TB equals to 1000 GB.

  • Essentially, if a hard disk is advertised as 1TB. Then, It contains 1 TB = 1000 * 1000 * 1000 = 1,000,000,000 KiloBytes of space.
  • The hard disk manufacturer thus advertises the disk as a 1 TB hard disk.

However, In Technically speaking the relation between them is mentioned as under.

b1Bit (b)=1 or 0 Binary Digit
B1Byte/Octet(B)=8bits (b)
KB1Kilobyte (KB)=1024Bytes (B)
MB1Megabyte (MB)=1024Kilobytes (KB)
GB1Gigabyte (GB)=1024Megabytes (MB)
TB1Terabyte (TB)=1024Gigabytes (GB)
PB1Petabyte (PB)=1024Terabytes (TB)
EB1Exabyte (EB)=1024Petabytes (PB)
ZB1Zettabyte (ZB)=1024Exabytes (EB)
YB1YottaByte (YB)=1024Zettabytes (ZB)
Bits & Bytes Relation Table

What 1 TB Means to our Computer System in technical terms.

At actual it contains actual bytes in 1 TB = 1024 * 1024*1024 * 1024 = 1,099,511,627,776 KiloBytes of space.

So, it means that actual 1 TB is 1,073,741,824 KiloBytes but instead we get 1,000,000,000 KiloBytes for 1 TB from the manufacturer. You might be wandering that the manufacturers are cheating with the people. They are providing less space than mentioned in their specs. But it’s not actually true.

According to our Traditional method for calculating unit. The International System of Units (SI) defined the prefix kilo as 1000 (103); as per this definition, one kilobyte is 1000 bytes. Same calculations follow for Mega, Giga & Tera Bytes also.

For decimal calculations 1000 decimal value is approximately near to the binary value of 1024. So 1 KB is considered 1000 Bytes approximately near to the 1024 actual Bytes. You know what the truth is? Both are correct on each of their respective sides.

Coming to the point where the remaining space gone?

Simple Answer is calculated as under. Actual space in terms of our computer shows we will get simply taking the space given from the manufacturer & dividing it by the actual space.

As per our system it takes space 1 TB given from manufacturer & divide it by actual 1 TB that system means.

So System Showing Space = (Manufacturer 1 TB) / (System 1 TB)

= 1,000,000,000,000 / 1,099,511,627,776

= 0.9094 TB

So here it means when 1 TB = 1,000,000,000,000 Bytes are given to us that means to the system 0.9094 TB

As for the system calculation 1 TB means 1024 GB.

= 0.9094 * 1024 = 931.2256 GB

Hence, we got the point why the system shows approximately 931 GB of space for 1 TB HDD. So, this how the mystery of 1 TB HDD shows 931 GB is solved.

Other Partitions

Laptops and Desktops often come with several partitions, including a hidden recovery partition. You might be wondering why a new computer has less free space ? You will find that space is taken up by a separate recovery partition.

To check for partitions & Management, use the Disk Management application which is inbuilt in Windows.

  • Click Start,
    • type partitions and
      • select the Create and format hard disk partitions shortcut to open it.


  • Press Windows key on keyboard ,
    • Type partitions and
      • Select the Create and format hard disk partitions shortcut to open it.

The hard drive should report its correct size in the Disk Management window. As we can say, nearly 11 GB of the hard drive’s space is reserved for a hidden recovery partition. This is fairly typical of laptops and other computers you don’t build yourself.

Each of the mentioned factor will take a space of your available hard drive space, leaving you with less space than expected for your own use.

Why computer shows the wrong amount of free space other reasons – Shadow Storage for restore points, Previous versions of files.

You’ll probably notice something odd about the amount of free space available on your hard drive, if you look closely. If you check your C: drive properties in Windows, you’ll see a certain amount of space referred to as “Used Space”.

If you select all the files after opening your C : drive (including hidden files and Windows system files) and select Properties. You’ll find that the amount of space used by files does not match with the amount of used space on your hard drive.

Here, if we have 272 GB of files on our drive & windows using only 279 GB of space.

where did all those 7 GB gone?

It turns out that certain types of files don’t appear in Windows Explorer. Files in the Windows are named as “shadow storage,” also known as “shadow copies,” & they don’t appear here. The shadow storage contains all the System Restore Points and also Previous Versions of files for the Previous Versions feature in Windows Explorer.

To view the exact amount of storage used by shadow files on every hard drive attached to your system, you can check it by running the below mentioned command. You’ll need to run it as Administrator – to open a Command Prompt window as Administrator, search for Command Prompt in the Start menu, right-click the Command Prompt shortcut and select Run as administrator.

Run the following command in the Command Prompt window :

vssadmin list shadowstorage

As From the above command, we will find that about some GBs of space is used in our hard drive by the Windows Shadow Copy Storage, To settle the amount of HDD space used System Restore and Previous Versions of files.

Follow this guide:

Make System Restore Use Less Drive Space in Windows 7

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