Why Do Hard Disk Drives show less than their Rated Capacity?

You must have come across a situation where the stated capacity of the hard disk drives did not match up with the one stated on its packaging. Certainly, it is not a defective card, but the cards and storage devices you purchase come along with a bundle of pre-loaded files. Also, the manufacturer is not cheating you by skimping the storage space or price.

The simple logic is the figures involved in maths and marketing strategies. The need for hard disk drives generally arises when there are either disk failures or at the time of purchase of a new computer system. However, disk failures can be dealt with various data recover services.

Read below and find out the possible reasons associated with the difference in actual storage capacity and the one advertised by the manufacturers.

  1. The Differences between Bits, Bytes, Terabytes, and Tebibytes:

Data in computers is stored in a binary format as one and zeros. Eight of these combine to form a byte and various amounts of disk storage capacities are represented with certain prefixes. These storage prefixes are at times similar to metric prefixes. Each level of binary represent base 2 and have an increment of 1024.

The common measures of binary prefixes are as follows.

  • 1 KB or Kilobyte equals 1,024 bytes
  • 1 MB or Megabyte equals 1,024 kilobytes or 1,048,576 bytes
  • 1 GB or Gigabyte equals 1,024 megabytes or 1,073,741,824 bytes
  • 1 TB or Terabyte equals 1,024 gigabytes or 1,099,511,627,776 bytes

The data is further stored in terms of sectors and clusters. Clusters are defined as small packets that can store chunks of data. Windows use 1024 as the base to compute the storage capacity of the drives, while manufacturers use 1000 as the base. Hence the different calculation bases lead to a varied capacity of the drive that is stated and advertised.

  1. Advertisement versus Actual:

The consumers find it difficult to understand the calculations made on the base 2. Therefore the manufacturers make use of base 10 while determining the storage capacity of the hard disk drives. One terabyte is equivalent to trillion bytes and one gigabyte equals billions of bytes. The problem of making possible approximations with bytes tends to increase with increased prefixes. These lead to enormous discrepancies between the actual space used and the one that is advertised.

The common levels of differences are stated hereunder.

  • The difference in Megabyte equal 48,576 bytes
  • The difference in Gigabyte equal 73,741,824 bytes
  • The difference in Terabyte equal 99,511,627,776 bytes

Based on these differential levels there are differences in the reporting of the storage capacities. But this is not the case with all the drives in the market. Hence the consumers ought to be careful with various storage drives. Certainly, the hard drives are reported in gigabytes format, while the flash disk drives are advertised with actual storage amounts.

  1. Formatted and Unformatted Disk Drives:

A bit of space on hard disk drives is taken up by formatting information between the sectors and clusters. The choice of disk drive entirely depends whether you are looking for a formatted disk or an unformatted one. These formatting schemes enable the computer systems to read and write the data on the disk properly.

Hence when a disk drive is formatted, the functional storage of the hard disk drive is less as compared to unformatted capacity. The amount by which space gets reduced is dependent on the type of formatting used for the drives and the size of the files stored on the disk drives and systems. They tend to vary on a large scale. Also, they are the main problems encountered by manufacturers while quoting the storage capacities of the flash drives.

Apart from the above considerations, specifications of the disk drives should be read before the initial purchase. Generally, manufacturers provide footnotes pertaining to ratings of the device specifications. These will help you a lot while selecting the right hard disk drive.