Thread: Why you don't get advertised space on HDDs

The problem is that while your computer calculates MBs and GBs as multiples of 1024. The companies calculate it in 1000s. So you lose 24KB every one MB.That's exactly the amount lost in the HDDs. Try calculating - Say you have a a 320GB HDD. So 320 GB = 320 x 1000 x 1000 KB = 320000000 KB. For your computer though: 320000000 KB = 320000000/1024/1024 = 305.18 GB. So that is the amount of spave you'll get on your HDD. Hope it clears some peoples confusion! PS: There's no such problem in RAM. Mostly what you see less is the video memory shared by your onBoard video card!

But they are not there advertised sizes. 1Gb for a computer is 1024, there is no way to change that fact. It's just there way of saving a little $$$. The same as Internet Providers and their advertised speeds.

Originally Posted by ajr1177

But they are not there advertised sizes. 1Gb for a computer is 1024, there is no way to change that fact. It's just there way of saving a little $$$. The same as Internet Providers and their advertised speeds.

No, desi is right. Hard drives have a different advertised size than actual size (320 GB advertised vs 305 GB actual, as desi's post mentions). The box says the drive is 320 GB, but it is actually only 305 GB.

For ISPs it's less of a lie and more of confusion through conversion (bits per second vs bytes per second). It's still the same speed, just a different way to display it: 8 Mb/s = 1 MB/s.

It's just that people are not aware of this mostly and always wonder where does the space go. Obviously you can blame the manufacturers for this. But there must be a reason why everyone is doing this. Not that I know of any such reason. May be its only a bid to save some expenses, but its out in the public. I wonder why there is not even one Manufacturer who brings out an HDD of actual size as he claims it to be!

Originally Posted by desipirate

It's just that people are not aware of this mostly and always wonder where does the space go. Obviously you can blame the manufacturers for this. But there must be a reason why everyone is doing this. Not that I know of any such reason. May be its only a bid to save some expenses, but its out in the public. I wonder why there is not even one Manufacturer who brings out an HDD of actual size as he claims it to be!

They round off the 1024 values to 1000 so that the capacity of the drives are nice equal numbers like 320GB or 500GB, instead of 305.25GB or 924.78GB. Plus, like you already said, it "tricks" the consumer into thinking that they are getting more than they actually are.

It's how binary works.. i forget how it works exactly; I saw it in a Newegg review. It's like computers can only read multiples of certain numbers, and 100x's are not those multiples.

Also remember, there is space for the MFT, PT, Formatting info....

Windows shows drive size in Bytes the same as the drive is advertised. when I bought my last drive it stated TB not Tb.

If windows showed your drive size in bits then my TB drive would show up as 8192Tb, because there are 8 bits in 1 byte.

The only reason they are not the advertised size is because the manufacturers use decimal and PC all use binary. They consider 1,000,000,000 a TB when it should be 1099511627776.

Don't forget drive density.
Since manufactures squeeze so much data on the same square inch of space, there is more chance that a sector will be "bad".
They also take away from usable space and save this space for any bad sectors that develop to move good data too.

seems pretty deceptive if you ask me.

if food manufactures tried to get away with that, say the box said 16 oz but it only contained 12 oz, and they tried to justify it by saying they were talking about metric ounces or some other excuse, the department of weights and measures would come down on them so fast it would make their head spin. yet hdd manufacturers are allowed to get away with doing essentially the same thing