How can I calculate hard drive space? (for Windows, MacOS)?

The actual hard disk drive space and the calculated hard disk drive space for Windows and Mac OS are different, therefore, errors are generated in the space displayed on the OS.

The spaces are the same between the actual and the one displayed on the OS.
Hard disk drives on the product catalogues are calculated for the sale as below;

1GB=1000×1000×1000 Byte

For Windows (MacOS), the formula is different as below;

1GB=1024×1024×1024 Byte

Therefore, the space displayed on Windows and MacOS looks smaller than the space of hard disk drives that you purchase but the actual space is the same size.

[The space displayed on Windows and MacOS]
For example, a 320GB hard disk drive is calculated as below:

(320×1000×1000×1000) ÷ (1024×1024×1024)= 298.0232.

Therefore, approximately more than 298GB should be recognized for the products.

Another example; a 400GB hard disk drive is calculated as below:

（400×1000×1000×1000) ÷ (1024×1024×1024）= 372.5290

Approximately, more than 372GB should be recognized for the products.

The same formula is applied for hard disk drives of different space. Refer to the chart below for differences in space among hard disk drives.

If the size of the space displayed on the OS is larger than the one shown in the chart below, then the product works properly.

*When the hard disk drive space is checked via [My Computer], it shows the space without the system area. Therefore, the displayed space may be smaller than the above space.

*The above formula is used for BUFFALO Storage Devices (excluding TeraStation/LinkStation).