Macbook not showing full disk space

I have:

1. 120 gig internal drive
2. 250 gig external drive
3. 320 gig external drive

but, in disk utilities it is reporting them as being

1. 111 gigs
2. 232 gigs
3. 298 gigs

what has is done with the extra space?

I think this question gets asked weekly. Nothing has been done with the extra space, it's simply a different way of mathematically expressing the same number of bytes. The difference being that the first instance uses base10 to determine the number of bytes in a kilobyte, megabyte, gigabyte, terabyte, petabyte etc and the latter uses base2. So, let me show you what I mean. If you open up terminal and use df -h this will show your drives in base2 (which is the default method for all operating systems to calculate space). As such:

mikeMbp:~ mike$ df -h
Filesystem Size Used Avail Capacity Mounted on
/dev/disk0s2 233Gi 154Gi 78Gi 67% /


and if you issue df -H this will show it in base10 (which is what marketing departments use):

mikeMbp:~ mike$ df -H
Filesystem Size Used Avail Capacity Mounted on
/dev/disk0s2 250G 166G 84G 67% /

There is plenty of information available on the net about this disparity, much complaining about how this is false advertising etc, when it's simply just a different expression of the same thing... for instance.. if I list the space by kilobyte it's still..

mikeMbp:~ mike$ df -k
Filesystem 1024-blocks Used Available Capacity Mounted on
/dev/disk0s2 243862672 161950284 81656388 67% /


or a two hundred forty-three million, eight hundred sixty-two thousand, six hundred and seventy-two kilobyte hard drive.. boy, that's a mouthful.

thanks mike,

i have always assumed that disc size worked in base 2 so 1024 bytes = 1 kilobyte etc,

so what you are basically saying is that the manufacturers are using base 10 to make the discs sound bigger than they actually are. bit cheeky really.

While I agree that the practice is dubious at best, it's unfortunately been agreed upon internationally and so we're stuck with it. I really wish that operating systems did base 10 by default as it would cause fewer people headaches.

And just to add confusion, the vendors often mix the bases. They use base2 up to 1024 bytes, but then shift to base10 from there up. So, a Megabyte is 1024*1000, not 1024*1024. Gigabyte is 1024*1000*1000, etc.

The funniest thing about this question is that we see it so often from switchers. This has been going on since hard drives became commonplace in PCs in the mid 80s, but many people don't notice it until they switch to Mac. No offense meant to anyone, but it's just an odd phenomenon that we see so often here.

@cwa197, it's not just switchers. I visit a couple of other boards, including Windows, PDA/Smartphone and digital camera ones, and this question comes up whenever anybody who doesn't know buys a new hard drive, or new storage card. We have to educate the universe one person at a time, apparently.

it would be handy if there was a setting to get the operating system to use base 10.

also, when you buy software and they say eg 10gig of hard drive space required, are they using base 10 or base 2?

bungy said:

it would be handy if there was a setting to get the operating system to use base 10.

also, when you buy software and they say eg 10gig of hard drive space required, are they using base 10 or base 2?

Click to expand...

Usually, yes. (I know that didn't answer the question, but it's about all we can say. It varies from vendor to vendor, package to package. The bottom line is, if your disk space is that tight, you need to buy a bigger drive!)