Advertised hard drive sizes

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Guest

Guest
Does anyone have a clue as to why the size of a hard drive as reported by Windows or DOS is always smaller than what the manufacturer advertises the drive size as?

For example, I just bought a notebook from Dell and the specs say it contains a 10 GB hard drive. Windows reports the size as only 9.08 GB.

I also have a 10 GB drive from Western Digital that I bought and installed in my desktop. Windows reports the size as 9.2 GB.

I've called Western Digital and Dell. They give me some excuse about windows not reporting the right size and the manufacturer using a different method to measure the disk capacity and Blah Blah Blah...

I've used partition magic to create a 10 GB partition from a 30 GB drive, so I know how many bytes it takes to make a 10 GB drive. The manufacturers always fall short of the advertised size.

Seems like false advertising to me.
 

Lars_Coleman

Distinguished
Feb 9, 2001
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Hard drive manufactures define a MegaByte as 1,000,000 bytes = 1MB and Fdisk in Windows defines it as 1,048,576 bytes = 1MB. If you do the Math it comes out smaller ...

Here's some useful information I had on hand :::

'The listed capacity is an unformatted (raw) capacity. After partitioning and formatting, actual storage capacities may vary depending on the operating system and configuration. Hard Drive mfg's adhere to the NIST and IEC definitions of Megabyte and Gigabyte.

Storage devices are marketed and sold in terms of decimal (base 10) capacity. In decimal terms, one Gigabyte (GB) is equal to one billion bytes. Most BIOS’s follow this definition as well. However, many operating systems use the binary (base 2) numbering system. That would be two to the thirtieth power, or 1,073,741,824 bytes equals one-Gigabyte.
According to the NIST and IEC standards, an 80 GB hard drive would contain eighty billion bytes. 80,000,000,000 bytes divided by 1,000,000,000 bytes equals eighty decimal Gigabytes. In binary terms, 80,000,000,000 bytes would be divided by 1,073,741,824 for a total of 74.5 binary GB. However, there are still 80 billion bytes on the drive in either case.
The IEEE Standards Board decided that IEEE standards will use the conventional, internationally adopted, definitions of the SI prefixes. Mega will mean 1,000,000, and Giga will mean 1,000,000,000 except that the base-two definition may be used (if such usage is explicitly pointed out on a case-by-case basis) until such time that prefixes for binary multiples are adopted by an appropriate standards body. You can find complete information on the International System of Units (SI) prefixes for binary multiples online at http://physics.nist.gov/cuu/Units/binary.html.'


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Guest

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Bit like a car engine at 5 litre when it could be 4.9L or 5.0L in the next model, same engine whatever. Just an approximate general Identification number that makes it easy reconizable.

:smile: Too damn hot in that kitchen!
 

silverpig

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Dec 31, 2007
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True about the formatting thing as well. Different filesystems take up different amounts of room on your drive as well. If you formatted your 10 gig drive entirely as ext2 and then reformatted it as fat32, you'd get different sizes.

Lyrics. Wasted time between solos.