Helping people with computers... one answer at a time.
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?
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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.
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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.
Article C2304 - March 13, 2005
Leo A. Notenboom has been playing with computers since he
was required to take a programming class in 1976. An 18 year career as a programmer at Microsoft soon followed.
After "retiring" in 2001, Leo started Ask Leo! in 2003 as a place for answers
to common computer and technical questions. More about Leo.
My recovery C Drive say It only has 45KB left. Is there any way I can add more memory to it? I have a Dell with window Vista.
Posted by: Roger Wheat at June 11, 2010 11:57 AMSomeone said - "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"
Umm
Kilo means exactly 1 thousand (not around)
MEGA means exactly 1 million (not around)
Giga means exactly 1 billion (not around)
Your math is spot on old bean, but how YOU think is wrong. and yes the companies sell you an 80 gb hard drive with only 7.6 gb usable ( by you) because the rest is used my your operating system.
When i had my old 486 Dx 33 ( loooong time ago) I had a 260 mb hard drive ( that was huge back then) Dos and windows 3.1)reported exactly 260 mb. it wasn't until the advent of Windows 95+ did the operating system hog space for it self.
So yes you ARE getting an 80gb hard drive, but your Operating system gets dibs on the other gigs. so windows is correct in telling you that you have 7.6gb of space. thats the space left over AFTER windows hogs what it wants.
Posted by: Steve at September 15, 2010 12:04 PM@Steve: Leo's math is correct, and so is his logic.
You're right, 'kilo' means 1000, etc.
But in computer terms, (and if you read his post carefully you'll find out), 'kilobyte' doesn't mean 1000 bytes, it means 1024, even though they use the prefix 'kilo'.
So when he says we humans says 'kilobyte' to mean 'around 1000 bytes', he's right - because 1024 bytes is very close to 1000, so in layman's language, we round it off to 1000 to make it easier for us to understand. But to a computer, a kilobyte is 1024 bytes. And a gigabyte is 1,073,741,824 bytes.
So if you have a computer that says '80GB' on the box, realize that this is 'human talk', so that companies can make it appear that they're giving away more memory than they actually are. In 'human talk', that's 80,000,000,000 bytes they're giving away. Which is correct. Want to find our how much you'll ACTUALLY get when the computer uses the disk?
Simply divide 80,000,000,000 by 1,073,741,824, and you'll get the result = 74,5 GB, which is exactly how much the computer reports.
The reason you see less memory is NOT due to the operating system, as you stated. The above happens even if the disk is completely clean and has no operating system on it whatsoever (I know because I have one hard disk with no OS on it.)
The reason your old computers reported the exact amount of memory that was available to the computer, was because in THOSE DAYS (80's), the manufacturers used 1024 bytes to mean a kilobyte. Later when they started selling 8GB drives upward, they started using the 'layman's' definition of KB, GB etc.
Geddit?
08-Nov-2010
Posted by: Feliciano at November 7, 2010 10:19 AM
You've touched on one of my pet peeves.
Sure, back in the "old' days, my $5000 386 included upgrades. All the way up to 80mb and 2mb of RAM. Back then there were a couple of things going on. Many vendors sold drives unformatted, so when you formatted the drive a lot of space evaporated. Other vendors would sell formatted drives that actually had a little more space than advertised because they expected sectors to go bad. And in those days, losing a sector was a significant bite out of the total drive size. So they hedged to keep customers happy.
The binary reporting in the OS was based on optimizing performance when CP speeds were measured in Khz and memory in 100's of bytes. The CPU and the RAM was binary, so it was "easier" for the computer to report in powers of 2. Conversion to decimal was "cpu expensive". But now when even "granny" has GHZ sitting idle on her desk I think it is time for the industry to convert to measure that is "normal" for "average" user. That is counting in decimal rather than binary. Powerful computers are now commodity items that are being marketed to "average people". Computing has grown way beyond geeks who count in binary and hex and who could read core dumps. Mom, Pop and grannies now use them on a daily basis.
My concern about the binary / decimal divide is the scale it is reaching. Sure 24 bytes isn't much in 1000 bytes, but since you are dealing with powers of 2 the gap keeps on getting bigger. That 1 TB (decimal) drive only has 931 GB reported in the OS. That "lost" 70 GB is a significant difference. It won't be all that many years when the home theatre server will be measured in petabytes.
Posted by: ron at November 16, 2010 6:27 PMIt's certainly one of the things that puzzles new computer users. A 500 GB Seagate drive I recently installed reported 465 GB of space. It's perfectly normal.
Posted by: Mark at November 17, 2010 5:22 PM