# 500 GB hard disk only has 465 GB



## JPLamb (Jan 27, 2005)

Hi

i recently bought a new 500 GB external hard disk and after plugging it in it only has 465 gb of space, i have seen this before on other external hard disks and was just woundering what happened to the 35 GB that is not available.

Cheers


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## Alex Ethridge (Apr 10, 2000)

The disk manufacturers lie. Seagate was sued in California last year for that very thing. Henceforth, they will be properly labeling anything sold in California. The rest of the country will continue to be lied to.

http://www.harddrive-settlement.com/

Always figure you're getting only 93% of the advertised size. And that is with all brands.


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## JPLamb (Jan 27, 2005)

Wow i didnt know they did that or even that they were allowed to get away with that, i have normally seen it on smaller drives and guessed that there were some system files of some sort on the disk but got a bit suspicious when 25 gb was missing from my drive.

cheers for the reply


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## Guest (Jul 31, 2008)

Hi JPLamb,

I don't know about the manufacturers lying, but I think it's more to do with the following:

The manufacturers and operating systems interpret the units differently. This explains it, somewhat: http://en.wikipedia.org/wiki/Hard_disk_drive#Capacity_measurements

I don't know much about it myself but basically, I think if i.e. you have a 500GB HDD (500GB stated by the manufacturer, calculated through its definitions), the OS through its definitions, calculates it as 465GB and the bigger the HDD, the more the difference. Both the manufacturer and the OS; however, will have the same definitions of i.e. a byte and will both state the drive as having i.e. 500,065,098,568 bytes. It's complicated but I don't think it's much to worry about (unless you go into somewhere like a HDD or OS manufacturing job lol) and I see it all the time.

Regarding system files, any stored on there may be hidden but will be included in the 465GB and any programming stored in the hard disk (to make it work) is totally separate from the 500GB storage, which will be stored in chips on the disk.

Hope this helps and have a great day,

Matthew.


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## taarno (Jul 29, 2008)

This is just a shot in the dark but i think some of te drive is kept spare incase the drive becomes corrupted and thats when the spare comes in to play hence the bigger the drive the bigger te discepancy. I dont mind if someone shoots that theory down.


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## Nick334 (Nov 4, 2007)

I thought it was to do with them using it as 1000 bytes in a megabyte rather than 1024 as it actually is. Something to do with 10^6 and 2^20. The difference gets bigger and you end up with 30GB less apparently. Don't worry about it anyway - it happens to everything.

(That might all be wrong, I have no clue really)


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## Guest (Jul 31, 2008)

Hi,

Not to say you're wrong taarno (and at work experience, my boss said a similar thing), but I couldn't find anything really on Google or on that wikipedia article on hard drives about them having spare incase of corruption, only about the different interpretations between the OS and HDD manufacturers and that when you multiply an error, you get a larger one, hence the exponential difference, which I've read and known about before, anyway, so it's probably more that, but that's got me thinking about if there are any fail-safe corruption features like that in them, hmm.
Maybe we should ask a HDD manufacturer, lol .
Anyway, I think it could be more the different interpretations,

Matthew.


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## dustyjay (Jan 24, 2003)

Actually the way the Gigabyte is calculated is exactly why the difference happens. The manufacturer uses 1000 as the base number to calculate drive space. Where as the number should be actually 1024 as was stated and is calculated by the OS. This is an arguement that has gone on for years.


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## Nick334 (Nov 4, 2007)

So I was right


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## Guest (Jul 31, 2008)

The manufacturers calculate the capacity of the disk with the IEC standard (1024) and the OS with the SI standard (1000), hence why the manufacturers state a larger value and at first, the difference is only 24, but with larger disks, that discrepency is multiplied, equalling a larger discrepency, a positive, exponential correlation between disk size and the apparent discrepency. This has led to confusion and legal battles with users believing they are getting not what was stated and the need for manufacturers to clarify the capacity stated on their products. In the OS; however, in a file, folder or drive properties, the IEC version (1024) is also stated. The 1000 is decimal, by the SI standard with kilo-(byte) (k(B)) mega-(byte) (M(B)) giga-(byte) (G(B)) etc. prefixes and the 1024 is binary, by the IEC standard with kibi-(byte) (Ki(B)) mebi-(byte) (Mi(B)) gibi-(byte) (Gi(B)) etc. prefixes. JEDEC also uses the 1024 binary values, but with the kilo- (K) mega- (M) and giga- (G) prefixes. 

Notes: (bytes) and (B) after the prefixes show the option, byte. Lowercase abbreviations are often used interchangeably. Manufacturers using the 1024 value, state i.e. 500GB not 500,xxx,xxx,xxx (x denoting unknown value) bytes, but the 1024 version in the OS (Windows) in a file, folder or drive properties would state it as 500,xxx,xxx,xxx bytes, not 500GB. This sort of thing often leads people to a lot of confusion and misunderstanding and clarification is sometimes needed. Undoubtedly manufacturers will have lied before, but surely not every? System files and programming are included in the capacity/totally seperate. Mostly, corruption/data recovery is totally separate from the capacity.

Sources: Me, Google, Wikipedia.

Me close(ish)?


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## matthew0155 (Jan 14, 2008)

i have a 320gb and only have 299, 21gb missing.. no big deal. I am only using 80gb anyway... What does piss me off is my 8gb ipod and my 8gb memory stick. My ipod only has only 7.1gb, and my kingston 8gb has only 7.4... With the ipod i could put like 10 more short videos with that 900mb! Whats worse is i could put like 100 000 more txt documents on my usb stick with that 600mb!!!!!!!


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## Guest (Jul 31, 2008)

Yes, that's annoying, it can especially be more obstructive with smaller drives lol.


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## Compiler (Oct 11, 2006)

Yeah, Seagate got sued by stupidity.

But this is why we're seeing a large number of 3GB PCs, because of the techinical "math" that effects 32bit OS with 4GB of RAM. 

The HD manufacture are stating their numbers correctly (in my book) but depending on the OS and type of format of the drive will also dictate how that drive space is formatted.
A FAT 32 120GB HD will not be formatted as efficent as NTFS is an example in which you'll lose even more space because of the huge block sizes.

Thus the HD makers leave it up to the OS to take care of this.

Here is an easy example. Remember those 3.5" HD-Floppy floppy disks for PCs? Those were technically 2mb floppies. They formatted to 1.44mb of space for PC, 1.4mb for Mac and 1.76mb for Amiga.


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## Alex Ethridge (Apr 10, 2000)

> I don't know about the manufacturers lying


The courts have decided Seagate engaged in deceptive advertising (i.e. lying). Read about it here. "Mega" denotes a binary number and a Megabyte has _never_ been 1,000,000 bytes (plain math). It has _always_ been 1,048,576 bytes (binary number). Disk manufacturers long ago made the decision to tell people that a Megabyte is 1,000,000 bytes in an effort to make people believe they were getting more than was actually in the package, sort of like advertising a "bakers dozen" and putting only twelve in the box.

Binary is determined by multiplying 2x2x2x2x2 . . . etc. and that gives you 1,048,576, not 1,000,000.

With whatever respect may be due Wikipedia, any portion of it that is at variance with the court ruling, it is irrelevant. The court is the final authority in the definition of binary number and they ruled against Seagate, saying Seagate's use of 1,000,000 bytes being a Meg as being deceptive.



> shot in the dark but i think some of te drive is kept spare incase the drive becomes corrupted


No disrespect intended; but, there is no such reserved space on the drive.



> I thought it was to do with them using it as 1000 bytes in a megabyte rather than 1024 as it actually is. Something to do with 10^6 and 2^20. The difference gets bigger and you end up with 30GB less apparently. Don't worry about it anyway - it happens to everything.


Exactly. And that is what the law suit was all about.


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