# Formatted capacity confused

Discussion in 'Mac Basics and Help' started by TheBonk, Sep 20, 2007.

1. ### TheBonk macrumors 6502

Joined:
May 22, 2007
Location:
Chicago
#1
I'm totally confused with how formatted capacity works. People say that the computer reads 1GB as 1024MB, but manufacturers say 1GB is 1000MB. Wouldn't what the computer reads be more? You get 24 MB more in 1GB.

So wouldn't the formatted capacity be more?

I would appreciate it if someone could help me understand this.

2. ### Eidorian macrumors Penryn

Joined:
Mar 23, 2005
Location:
Indianapolis
#2
1000^3 bytes (Physical GB) / 1024^3 bytes (Binary GB)

3. ### mkrishnan Moderator emeritus

Joined:
Jan 9, 2004
Location:
Grand Rapids, MI, USA
#3

A little knowledge is a dangerous thing.

A computer considers 1GB = (1024)^3 bytes.

A hard drive actually has 1GB = 10^9 bytes.

So you have it sort of backwards. A byte is a byte. Each gigabyte on the hard disk is "shorted" by 1024^3 - 10^9 bytes, from the OS's perspective. So, if you have 160x10^9 bytes, you have a number smaller than 160GB in OS-speak. The number is 160GB x 10^9 / 1024^3.

Don't be too lazy. Write the algebra out for yourself. It's easy to see if you stop and write it out carefully.

4. ### Eidorian macrumors Penryn

Joined:
Mar 23, 2005
Location:
Indianapolis
#4
It's not algebra. At worst it's division and scientific notation.

5. ### mkrishnan Moderator emeritus

Joined:
Jan 9, 2004
Location:
Grand Rapids, MI, USA
#5
Well, put some variables and text in to make it clearer. But unless the original poster has less than a seventh grade education, it should be fairly straightforward....

6. ### Eidorian macrumors Penryn

Joined:
Mar 23, 2005
Location:
Indianapolis
#6
(1000 x 1000 x 1000) [Physical GB] / (1024 x 1024 x 1024) [Binary GB]

Kilo -> Mega -> Giga

http://en.wikipedia.org/wiki/Binary_prefix#Consumer_confusion

7. ### mkrishnan Moderator emeritus

Joined:
Jan 9, 2004
Location:
Grand Rapids, MI, USA
#7
8. ### Eidorian macrumors Penryn

Joined:
Mar 23, 2005
Location:
Indianapolis
#8
I'll just wait for a reply. They've been viewing this thread for some time now.

9. ### TheBonk thread starter macrumors 6502

Joined:
May 22, 2007
Location:
Chicago
#9
I think I get it now. The computer thinks it needs more MB to have a full GB. So it eats up more of the space. While manufacturers think you need less MB you have a full GB.

10. ### Eidorian macrumors Penryn

Joined:
Mar 23, 2005
Location:
Indianapolis
#10
The manufactures express storage in 10^x while actual data storage is in 2^x.

### Staff Member

Joined:
Aug 16, 2005
Location:
New England
#11
Shouldn't that be (2^10)^(x/3), so x can be the same as in 10^x.

2^10=1024 for those who don't know.

B