Hard drive capacity calculator. Real vs claimed

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 Claimed  Capacity
4 TB
 Real Capacity
12 TB
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Hard drive capacity calculator

As a hard drive or SSD user, you need to know the real capacity of your drive. When it comes to the advertised storage space is not the same as the amount of space actually available. To help you find the exact amount of usable space, Platinum Data Recovery has developed two tools: Hard Drive Capacity Calculator and RAID calculator. This free and super-easy-to-use tool can quickly calculate the space available in your hard drive.

How to use calculator

To use this calculator, simply enter your parameters. You need to select the unit of storage and your device’s claimed capacity. In the result section, you can choose the storage unit in which you want to see the result. Once you enter these few details, you will get the real capacity result within a fraction of seconds. This tool will help you find out how much data you can store in your drive, as well as how many kilobytes are in a gigabyte. Whether your hard drive’s storage is labeled in GB or TB, you can calculate it in other units of measurement.

Example of calculator use

For instance, if you enter 64 GB in the claimed capacity section and want results in GB, your drive’s real capacity will come out as 59.6 GB. Likewise, if for the same 64 GB drive, you want to get results in MB, the calculator can quickly provide you with real available space as 61035.16 MB. Now let’s take a quick look at the claimed capacity of the drive and the actual real capacity.

Why real capacity is less than claimed capacity?

Now you might be wondering why the advertised HDD storage does not match the usable data capacity. Most hard drive or SSD users have the same question- why actual drive capacity is lower than the space mentioned on the label? But before you blame the drive manufacturer for giving false information, it’s important to know the reason behind this capacity discrepancy. So, let’s find out how the capacity of hard disk drives is calculated and why their actual size differs from the advertised size.

To know why it happens, you need to know the difference between the Decimal system and the Binary system. Hard drive manufacturers advertise their products in the decimal system. But our operating systems, such as Windows or older MacOS, are based on binary math, which means storage is counted using base 2, not base 10, which storage is advertised as. This means that for the computer system, a KB is 1024 bytes, while for a hard disk manufacturer, one KB is 1000 bytes.

Since your computers work on the binary system, there is an increment of 2 to the 10th power or 1,024 in each storage level. Therefore, in the computer system:

Kilobyte (KB) = 1,024 Bytes
MegaByte (MB) = 1,024 Kilobytes or 1,048,576 Bytes
Gigabyte (GB) = 1,024 Megabytes or 1,073,741,824 Bytes
Terabyte (TB) = 1,024 Gigabytes or 1,099,511,627,776 Bytes

If you are interested to know more, we wrote a dedicated article on why drives show less capacity than advertised.