HDD's - the Advertized size vs the Actual size.

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Excellent explanation for non informed people.
+reps

mmmm, from looking at this, you get 1extra gig if you buy a TB disk vs. two 500's ?

myzr7 said:

mmmm, from looking at this, you get 1extra gig if you buy a TB disk vs. two 500's ?

Click to expand...

Sorry myzr7, actually not.

The real right size of 465 gb = 456,60
If I applied strict rounding, it would be 466 gb
But to not make it to confusing I rounded them the way Windows shows them.

Greetz

Darn just lost that gig. thanks for clearing that up. As said before very good info.

In case anyone is interested in why this difference exists, here's a bit of background.

Computers have address registers that are binary objects, and thus can address quantities as powers of 2. So, in the early days, when "large" numbers like 1024 came into common use, the prefix "kilo" was used because 1024 is "close enough" to 1000 (the "real" kilo) to "borrow" the prefix for talking about RAM.

There were objections even then to that use of the "kilo" prefix but the usage continued.

Time goes on and capacities increase. Now we talk about Kilobytes, Megabytes, Gigabytes, Terabytes, each time multiplying the previous number by 1024. Do that a few times and the difference between the decimal meaning of the prefix and the commonly used computer meaning of the prefix drifts further and further apart until you get a "gigabyte" that is 1,073,741,824 bytes.

But the non-computing world still uses these prefixes in their historical, decimal sense of 10^3, 10^6, 10^8, 10^12 etc. And the computing and non-computing worlds intersect.

One of those intersections is in description of disk capacity. Hard drive, CD, and DVD capacity are given using the decimal meaning of giga- etc. prefixes. Interestingly, flash cards, which are a kind of RAM, have capacities stated with decimal prefixes like hard drives.

Data transmission rates (such as ethernet speeds) and volumes are also stated using decimal meanings of prefixes.

It was proposed that the prefixes for computer/binary-derived counts be changed, e.g., using "gebi-" instead of "giga-". I've not seen that proposal in any use.

Guy

I've always liked the reviews at NewEgg where the person says, "This drive is awesome, but it only formatted to xxx GB's". As if some are bigger and some are smaller.

Those folks need to come here and read this thread....

Nice job squonksc. I thought this looked familiar.

There's another way to calculate the advertised to actual though with the ratios you might want to add to your above post.

Just multiply the advertised size with the correct ratio.




(kilobyte Example - 500.000.000.000 byte multiplied by 0.9765625 = 488.28125
488.281.250 kbyte multiplied by 0.9765625 = 476.837158203125
476.837 Mbyte multiplied by 0.9765625 = 465.6611328125)

Kilobyte - 0.9765625

Megabyte - 0.9536743

Gigabyte - 0.9313226

Terabyte - 0.9094947

Petabyte - 0.8881784



So, let's say I have an advertised HDD size of 500GB, and want to find the actual size that you'll see..


500GB multiplied by 0.9313226 = 465.6613

Thanks Airbot,
I am doing some shopping for a external drive and your numbers will help me with my cost analysis.

Airbot said:

Nice job squonksc. I thought this looked familiar.

There's another way to calculate the advertised to actual though with the ratios you might want to add to your above post.

Just multiply the advertised size with the correct ratio.




(kilobyte Example - 500.000.000.000 byte multiplied by 0.9765625 = 488.28125
488.281.250 kbyte multiplied by 0.9765625 = 476.837158203125
476.837 Mbyte multiplied by 0.9765625 = 465.6611328125)

Kilobyte - 0.9765625

Megabyte - 0.9536743

Gigabyte - 0.9313226

Terabyte - 0.9094947

Petabyte - 0.8881784



So, let's say I have an advertised HDD size of 500GB, and want to find the actual size that you'll see..


500GB multiplied by 0.9313226 = 465.6613

Click to expand...

*Gulp* Petabyte....

I can't even fill 100GB (that will soon change I hope)

Zidane24 said:

I can't even fill 100GB

Click to expand...

My MP3 folder is larger than that.

I will be the first to admit that I have an OCD where computers are concerned...Everything has to be organized in set categories, any increase in space that I was not aware of drives me nuts, and any bit of desktop and/or Superbar clutter drives me insane. You will rarely find more than 6 icons on the Superbar for me and no desktop icons at all. If I need to run an app I just type it in the search bar of the start menu.

I shutter when I see some desktops on here

Airbot said:

Nice job squonksc. I thought this looked familiar.

There's another way to calculate the advertised to actual though with the ratios you might want to add to your above post.

Just multiply the advertised size with the correct ratio.

(kilobyte Example - 500.000.000.000 byte multiplied by 0.9765625 = 488.28125
488.281.250 kbyte multiplied by 0.9765625 = 476.837158203125
476.837 Mbyte multiplied by 0.9765625 = 465.6611328125)

Kilobyte - 0.9765625

Megabyte - 0.9536743

Gigabyte - 0.9313226

Terabyte - 0.9094947

Petabyte - 0.8881784

So, let's say I have an advertised HDD size of 500GB, and want to find the actual size that you'll see..

500GB multiplied by 0.9313226 = 465.6613

Click to expand...

Thanks Airbot,

My first intention was to place the ratios you gave when I wrote the piece,
but I feel for most people, the universal divide by 1024, is much easier to understand and remember than the ever changing ratios.

With the average (noob) user in mind, I thought I'd keep it as simple as possible.

But if people here think it should be added I am willing to put it in.

Let me know.

Greetz

I'd say you could just have your way as the first option, then put the ratio example as the second option, and let the user decide which way is best for them.

But, it's your thread, up to you.

Airbot said:

I'd say you could just have your way as the first option, then put the ratio example as the second option, and let the user decide which way is best for them.

But, it's your thread, up to you.

Click to expand...

Ok, I'll put in.

There are actually terms for the computer worlds version of Kilo and Mega...

The drive companies are using the correct term when they say 500 Gigabytes. But when your computer says it is only 465 Gigabytes, that number is wrong for the above mentioned reasons. But.. In 1998 a set of terms to use when refering to the base 2 "versions" of the standard decimal prefixes were defined but have never really been adopted.

Windows SHOULD be reporting the values as "Kibibytes", "Mebibytes", Gibibytes", "Tebibytes" and so on.

So your 500 Gigabyte drive is a 465 Gibibyte drive.

The binary terms are abbreviated such as "KiB", "MiB", "GiB" and "TiB" instead of "kB", "MB", GB" and "TB".

Airbot said:

I'd say you could just have your way as the first option, then put the ratio example as the second option, and let the user decide which way is best for them.

But, it's your thread, up to you.

Click to expand...

Done.

I left the Kbyte and Mbyte ratios out since there are no HDD's that are measured in those any more.

I also left out PByte, but will add it as soon as the first PByte disk can be bought by us earthlings.

Greetz

squonksc said:

You meant it right, but you said it wrong.

The manufacturers use the wrong terms.

They should say 500 Gigibyte

Windows reports it correct with 465 Gigabyte

Click to expand...

No I'm right.

The manufacturers are reporting true decimal Gigabytes or 500*1000^3 bytes which is the tru capacity of the drive.

Windows reports 465 Gigabytes (GB) but that is actually wrong. What Windows /should/ say is that it is 465 Gibibytes (GiB) (465 * 1024^3)

Windows and Linux and all computer filesystems are actually reporting all values in true KiB, MiB and GiB, but because no one knows what those mean they improperly use the terms kB, MB and GB.

fseal said:

squonksc said:

You meant it right, but you said it wrong.

The manufacturers use the wrong terms.

They should say 500 Gigibyte

Windows reports it correct with 465 Gigabyte

Click to expand...

No I'm right.

The manufacturers are reporting true decimal Gigabytes or 500*1000^3 bytes which is the tru capacity of the drive.

Windows reports 465 Gigabytes (GB) but that is actually wrong. What Windows /should/ say is that it is 465 Gibibytes (GiB) (465 * 1024^3)

Windows and Linux and all computer filesystems are actually reporting all values in true KiB, MiB and GiB, but because no one knows what those mean they improperly use the terms kB, MB and GB.

Click to expand...

Yup, you're right.

Was turning around things myself. Sorry.
(i'll delete my previous post)

But still it's a rip off by the manufacturers because every thing else in the computer world is using the Kilo, Giga and Terra.

1 Gbyte of memory = 1 Gbyte of memory.

1 Gbyte of diskspace = 0.9313226 Gbyte of diskspace

So it is very convenient for them to make this exception in their favor.