How come Capacity says 28.1GB and not 32GB?

MrMacBookPro

macrumors 6502
Original poster
Sep 23, 2012
269
0
FL
Just found this under "General"- "About"...

I under stand programs take up space and memory but shouldn't capacity be 32GB? just curious.. thanks
 

rwilliams

macrumors 68040
Apr 8, 2009
3,604
694
Raleigh, NC
Just found this under "General"- "About"...

I under stand programs take up space and memory but shouldn't capacity be 32GB? just curious.. thanks
The operating system and the preloaded Apple apps are taking up that initial difference in free space. It's no different from buying a new hard drive and loading Windows, OS X or Linux on it - the space you have left for storing files and such is going to be less than there was fresh out of the box.
 

darster

Suspended
Aug 25, 2011
1,703
1
Because there are really 1024 MB in a GB. Vendors however, use 1000 MB to a GB. Then add the apps and os and you will have less than 32 GB. In fact with a totally clean phone with nothing on it, your true capacity is 31.25 GB.
 

dasx

macrumors 65816
Jun 18, 2012
1,098
17
Barcelona
They say it's a 32GB device. That's true although they use 10^x instead of 2^y.
That is:

Reality (2^y):
1B = 8 bits.
1KB = 1B*2^10 = 1024B.
1MB = 1KB*2^10 = 1024KB.
1GB = 1MB*2^10 = 1024MB.
So 32GB = 32 * 1GB = 32 * 1*2^(10*3) = 32 * 1.073.741.824 = 34.359.738.368B

Now, they tell you it's a 32GB capacity but they use 10^x:
1B = 8 bits.
1KB = 1B * 10^3 = 1000KB.
1MB = 1000KB.
1GB = 1000MB.
So 32GB = 32 * 1GB = 32 * 1.000.000.000 = 32.000.000.000B

Let's calculate how much that actually is:

32.000.000.000B / 1024 = 31.250.000KB
31.250.000KB / 1024 = 30517,59MB
30517,59MB / 1024 = 29,8GB

So the actual capacity of the 32GB iPhone is 29,8GB. Now add the iOS and some default apps and it'll go down to the 28.1GB you see.
 

fat jez

macrumors 68000
Jun 24, 2010
1,657
207
Glasgow, UK
It's something the hard disk manufacturers started years back. Their marketing departments realised if they used the base 10 to represent capacity instead of base 2, they could market the disks as being bigger than they really were.

Sadly, this has become a de facto standard, even OSX uses Base 10 to report disk capacity (so it matches what is printed on the label).
 
Last edited:

megapopular

macrumors 6502a
Aug 21, 2007
737
10
Just found this under "General"- "About"...

I under stand programs take up space and memory but shouldn't capacity be 32GB? just curious.. thanks
Also keep in mind that future updates for your current phone should be larger files so that number will shrink further. I wonder how large ios 12 will be, 6-8gbs??
 

BFizzzle

macrumors 68020
May 31, 2010
2,443
0
Austin TX
but....but....he didn't use a smiley......
How am I supposed to keep up with all this sarcasm and humor if you don't use smiley's?
you are true on that.
maybe he was serious.sorry didnt mean to come off rude.

i just dont think anyone who would use the word debacle would be dumb enough to think the reason of smaller amounts gbs than advertised was due to a manufacturing error. (no offense OP)

maybe its just that im a sarcastic person and read it naturally with sarcasm :p
 

vastoholic

macrumors 68000
Jan 28, 2009
1,957
0
Tulsa, OK
you are true on that.
maybe he was serious.sorry didnt mean to come off rude.

i just dont think anyone who would use the word debacle would be dumb enough to think the reason of smaller amounts gbs than advertised was due to a manufacturing error. (no offense OP)

maybe its just that im a sarcastic person and read it naturally with sarcasm :p
You didn't come off rude to me. Don't worry about that. I probably read it too seriously. Oh well. Perhaps I'll never know unless FieldingMellish comes back in here.
 
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