Hard drive showing wrong capacity? Here's why.

[alanebro82]

Must not forget that while it is true to some degree that manufacturers use base 10 for ease of use... they also use it because it produces larger numbers. It would not require much effort for manufacturers to convert to the system that all computers use, in order to represent the total amount, but 150GB sounds much better than 139.7GB to the average consumer.

[Efrain16]

Originally Posted by HAL9000 Since we get numerous threads on this subject, I thought I would post this and sticky it.. hope it helps understand why hard drives don't format to their advertised capacity. Determining drive capacity can be confusing at times because of the different measurement standards that are often used. When dealing with Windows and Mac based systems, you will commonly see both decimal measurements and binary measurements of a drive's capacity. In either case, a drive's capacity is measured by using the total number of bytes available on the drive. As long as the drive displays the correct number of bytes (approximate), you are getting the drive's full capacity. Decimal vs. Binary: For simplicity and consistency, hard drive manufacturers define a megabyte as 1,000,000 bytes and a gigabyte as 1,000,000,000 bytes. This is a decimal (base 10) measurement and is the industry standard. However, certain system BIOSs, FDISK and Windows define a megabyte as 1,048,576 bytes and a gigabyte as 1,073,741,824 bytes. Mac systems also use these values. These are binary (base 2) measurements. To Determine Decimal Capacity: A decimal capacity is determined by dividing the total number of bytes, by the number of bytes per gigabyte (1,000,000,000 using base 10). To Determine Binary Capacity: A binary capacity is determined by dividing the total number of bytes, by the number of bytes per gigabyte (1,073,741,824 using base 2). This is why different utilities will report different capacities for the same drive. The number of bytes is the same, but a different number of bytes is used to make a megabyte and a gigabyte. This is similar to the difference between 0 degrees Celsius and 32 degrees Fahrenheit. It is the same temperature, but will be reported differently depending on the scale you are using. -------------------------------------------------------------------------- Various Drive Sizes and their Binary and Decimal Capacities Drive Size in GB Approximate Total Bytes Decimal Capacity (bytes/1,000,000,000) Approximate Binary Capacity (bytes/1,073,724,841) 10 GB 10,000,000,000 10 GB 9.31 GB 20 GB 20,000,000,000 20 GB 18.63 GB 30 GB 30,000,000,000 30 GB 27.94 GB 40 GB 40,000,000,000 40 GB 37.25 GB 60 GB 60,000,000,000 60 GB 55.88 GB 80 GB 80,000,000,000 80 GB 74.51 GB 100 GB 100,000,000,000 100 GB 93.13 GB 120 GB 120,000,000,000 120 GB 111.76 GB 160 GB 160,000,000,000 160 GB 149.01 GB 180 GB 180,000,000,000 180 GB 167.64 GB 200 GB 200,000,000,000 200 GB 186.26 GB 250 GB 250,000,000,000 250 GB 232.83 GB ---------------------------------------------------------------------------------------------------------------- Please note his thread is NOT FOR INDIVIDUAL QUESTIONS - please start your own thread if this sticky does not answer your question - but is open for discussion if anyone has anything to add.

Common reason why harddrives do not show up the right capacity:
FAT16 File system: Max 2GB partitions (I think this counts FDisk with no large disk support)
FAT32 (on Win9X): 2 TB (Terrabytes)
FAT32 (on Win2000 and XP): 32Gb
NTFS (Pre SP1 installer): 127GB (or there abouts.)
NTFS (SP1 or higher): 2 TB

Try to check BIOS constraints, and maybe update to a newer versions. Many very, very old BIOS's can't go above 8GB (or even 2Gb in some cases), and some older ones have a ~32GB limit. Some boards also hit rock bottom at about 128GB.

[0anna0]

I've got 2 partitions and I am on dual boot.

Unfortunately there's this 4MB that I couldn't use. But now I've got an answer to my problem.

Thanx guys...