Why aren't storage media at full capacity

[PM that]

During the last boxing day, I bought a 160gb external HD only to find out that it has a capacity of 149Gb. I also got an internal HD (suppose to be 250Gb) and it ended up being 230Gb. I recently bought a Sandisk SD memory card too (512mb) and it turns out that its 483mb.

My question is why aren't storage media at full capacity? I know they can't always be exact but there seems to be something wrong if it's 10 - 20 Gb off the mark. :mad:

[rilhouse]

it's because there is 1024 MB in 1GB, not 1000MB. base 2 vs. base 10

[toalan]

I always thought it was because part of the space on any drive is reserved for a File allocation table or something like that.

[willy]

Yeap .... HD makers will tell you 250GB = 250 x 1000 x 1000 x 1000 bytes but in 'real life' 250GB = 250 x 1024 x 1024 x 1024 bytes.

[deep]

A billion sure aint a billion anymore. Well, it is, but....

[kAMiKaZe]

During the last boxing day, I bought a 160gb external HD only to find out that it has a capacity of 149Gb.
Interesting you are short 11gigs...

I have a 200GB SATA drive formatted under NTFS and I am short exactly 10.3GB.. very close to the same number as you.

[hardcore]

you do lose storage due to file allocation tables and other overhead but the main loss is due to marketing.

250GB is really 250,000,000 bytes which is really 238GB.

[kAMiKaZe]

you do lose storage due to file allocation tables and other overhead but the main loss is due to marketing.

250GB is really 250,000,000 bytes which is really 238GB.
Isn't it 244.14GB?

250GB/1024*1000 ? Or am I calculating wrong?

[Firestorm ZERO]

250,000,000 / 1024 / 1024 = 238 GB

[goob3r]

Isn't it 244.14GB?

250GB/1024*1000 ? Or am I calculating wrong?

willy posted the formula.

[kAMiKaZe]

I see my miscalculation now..

Isn't memory the opposite of this problem? I seem to recall that my memory is 1GB.. but instead of being 1,000MB/1,000,000bytes it is actually 1,024MB or 1,048,576bytes?

So why are harddrives the opposite.. that instead of being MORE harddrive space, they actually give you less?

[hardcore]

memory is the correct way of counting storage capacity. but then you get memory in actual sizes like 4MB or 32MB or 128MB but not 60GB...

And when you get 4MB memory it's 4096Kb which is the actual amount to make 4MB.

With hard drives, if you actually have 50GB, you would actually have 52,428,800 bytes. You don't have more than 50GB... 50GB = 52,428,800 bytes. But the marketers saw this as just rounded everything down and say that is a 52GB drive, when in reality it's a 50GB drive, because 50GBs have over 52 million bytes.

[hardcore]

the same trick is done in car engines.

car manufacturers will claim that they have a 1.8L engine when it's only 1797cc.

[PM that]

Even after the calculations (in actuality 238Gb instead of 250Gb), I'm still missing like another 8Gb. Thats alot of HD space in my opinion.

[B0000rt]

the same trick is done in car engines.

car manufacturers will claim that they have a 1.8L engine when it's only 1797cc.

That's not really a "trick"

What's ******** with Automobiles is not the rounding of displacement, but horsepower specs are given at the CRANK.

WHo the hell cares about at the crank? What would be smart is to have testing done for wheel horsepower.

[Firestorm ZERO]

Even after the calculations (in actuality 238Gb instead of 250Gb), I'm still missing like another 8Gb. Thats alot of HD space in my opinion.

Are you using FAT? If so, the cluster size is high and so the file system can be taking up alot.

[PM that]

Nope....NTSF

[PM that]

Nope...NTFS

[zerocool24]

with a hard drive you will only get 93% of the advertised size 20=18.6 40=37.2, 100=93, 120=111, 160=149, 200=186, 250=232.5 etc for the reasons mentioned above.

[gman]

Nope...NTFS
8GB are for the overhead of the file system.