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Why isn't there 80 gigabytes of free space on my empty 80 gigabyte drive?

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I have just purchased a new computer with an 80 GB hard drive, and When I was installing Windows XP Home edition it said I had 76,000 MB of disk space. I don't get it. Shouldn't it be 80,000 MB? Is there anything I can do to recover the other space? If I go to My Computer in windows XP and Click on the Hard drive symbol it will show me the space on the hard drive. It said the total available space is 74 Gigabytes. What happened to the other six gigabytes?

They were never there.

Believe it or not, there's no real agreed upon definition of what a gigabytes is.

Let me clarify: there are definitions. Plural. And which one gets used depends on ... well, it depends on how you think.

The fundamental problem stems from the fact that computers think in powers of 2 (1, 2, 4, 8, 16 and so on), while people think in terms of powers of 10 (1, 10, 100, 1000 and so on).

So to a computer, a kilobyte is 1024 bytes (2 to the 10th power). A megabyte is 1,048,576 (1024 times 1024, or 2 to the 20th). And a gigabyte is 1,073,741,824 (1024 times 1024 times 1024, or 2 to the 30th). Thus 80 gigabytes to a computer is 85,899,345,920 bytes.

But as I said, people don't think like that. We think of a kilobyte as "around" 1,000 bytes. Close. Close enough for most conversations. But when we think of a megabyte as "around" 1,000,000 bytes, and a gigabyte as "around" 1,000,000,000 bytes, we're getting less and less accurate at each step along the way.

To a computer, 80,000,000,000 bytes is really ... 74.5 gigabytes.

SO... if you're going to sell a hard drive that holds 80,000,000,000 bytes, and you have the opportunity to call it 80 gigabytes (in human terms) or 74.5 gigabytes (using computer terms), which would you choose?

"80" sure sounds like you're getting more for your money than "74.5", doesn't it?

One last point: even though what I just described is the major reason for the discrepancy, there are other things that contribute to even less space actually being available. On a completely empty hard disk, the operating system will reserve some amount of space for its own use. For example the top level directory structure, even if empty, takes some space. Security information, the recycle bin, and other information is placed on the hard disk before you ever create your first file. Exactly how much will vary depending on how the disk is formatted. And finally, if this is your system drive, the operating system will also place certain hidden files that can get quite large, including your swap file, for virtual memory, and if you have hibernation enabled, the hibernation file.

Related:

Article 3394 | Posted March 13, 2005

Recent Comments

The 130gb limitation is due to lba limitations. Go here for help: http://www.48bitlba.com/

Posted by: Tom Barrister at January 21, 2006 02:44 PM

We have just bought an 80Gb Dell Inspiron laptop. The disk properties states total 69Gb, which it says is 74,***,***. I could understand if it said 80,***,*** was 74Gb, but how can 80Gb capacity be claimed for our drive which is 11Gb short?

Posted by: Michael Fletcher at January 23, 2006 08:58 AM

as i know... we define giga as 1000M, mega as 1000k and kilo as 1000
but pc define giga as 1024M, mega as 1024k and kilo as 1024

Posted by: ricky at April 20, 2006 02:07 AM

why there is no free space for me??i need extra space for my mail boxwhich is only 2MB. i need fast. do kindly give me free space or help me. thankyou for your co-operation

Posted by: mifrah at April 21, 2006 10:25 PM

Thank you for the explanation Leo. I was also stumped to where my extra GB's had disappeared to.

Posted by: Matt at May 27, 2006 04:28 AM

what i would like to know is why would windows xp say theres 1 mb or so of free space when i defragged the crap out of it and transferred all the big programs and files to my other drive?

it don't make sense

Alan
http://www.helio.com

Posted by: heliodude at August 15, 2006 06:36 PM

Well, for one thing, defragging does not free up disk space. That's not what it's for.

Posted by: Leo Notenboom at August 15, 2006 07:05 PM

My computer has been messing up lately. Sometimes the internet would work and sometimes it won't. What is wrong with my computer? Also, my new computer (less then 6 months)started with 232 GB free space on my hard drive and some things have been downloaded but not much. These things that have been download have taken about 30 GB of free space on my hard drive. One day after i was finished using my computer i checked the free space and it had 202 GB of free space on my hard drive left. When i logged back on my computer the next day the free space on my hard drive was 70.5 Gb. How is this possible? Also what does System restore do? (Start, all programs, accessories, system tools then system restore) I have done this before and it loaded my info and all but the programs that i installed before the date selected. Does this take a large amount free space off my hard drive because when my computer shut down again i tried to restore it to an earlier date and it took hours to restore it, sometimes it just stops trying to restore my previous works, it says "needs more virtual memory". Please help. My computer is being stupid.

Posted by: Nikki at October 31, 2006 09:14 PM

could you pls tell that when i delete any file and even remove it from recycle bin.....then using system restore ..i am able to bring it back...how does it work...are the files not deleted in reality?

Posted by: manish at November 3, 2006 02:46 AM

"We have just bought an 80Gb Dell Inspiron laptop. The disk properties states total 69Gb, which it says is 74,***,***. I could understand if it said 80,***,*** was 74Gb, but how can 80Gb capacity be claimed for our drive which is 11Gb short?"

Most Dell computer systems have a portion of the disk sectioned off..called a partition. They do this because they usually put system restore files in it, which include drivers and sometimes the OS as a cd/dvd image. So part of that space is likely that. The rest is likely taken up by Windows and windows related files ... and possibly by any pre-installed software/drivers.

Posted by: Adarious at April 11, 2008 01:42 AM

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